Process for producing a polymer by polymerization of a monomer having an ethylenic double bond

ABSTRACT

A process for producing a polymer by polymerizing in a polymerization vessel a monomer having an ethylenic double bond is provided. In this process, the polymerization vessel has a polymer scale preventive coating film on its inner wall surfaces and other surfaces with which the monomer comes into contact during polymerization. The coating film is formed by coating a first coating liquid containing a compound selected from the group consisting of an aromatic compound having 5 or more conjugated  bonds and a heterocyclic compound having 5 or more conjugated  bonds and a second coating liquid containing at least one hydrophilic compound selected from the group consisting of a water-soluble polymeric compound, an inorganic colloid, an inorganic salt and an acid; the first coating liquid and the second coating liquid being simultaneously coated by means of steam as a carrier. This process can shorten the time for forming coating films of scale preventive agents to improve productivity, can improve the effect of preventing scales, can make colored particles less mix into polymer products obtained by this process, can lessen fish eyes and initial discoloring of formed products and can improve the quality of polymeric products and their formed or molded products.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for producing a polymer bypolymerizing in a polymerization vessel a monomer having an ethylenicdouble bond, and particularly a process that can prevent polymer scalesfrom adhering to polymerization vessel inner wall surfaces and othersand can produce polymers having a good quality.

2. Description of the Prior Arts

As known in processes for producing polymers by polymerizing monomers inpolymerization vessels, there is a problem that polymers may adhere topolymerization vessel inner wall surfaces and others in the form ofscales.

Such polymer scales having adhered to polymerization vessel inner wallsurfaces and others may cause a decrease in yield of polymers, adecrease in cooling capacity of polymerization vessels, and a loweringof product quality when polymer scales having adhered come off to mixinto polymer products, and also may bring about a disadvantage that muchlabor and time must be taken to remove the polymer scales.

Moreover, since the polymer scales contain unreacted monomers, there isa possibility that operators are exposed to them to cause physicaldisorder.

Accordingly, in the polymerization of monomers having ethylenic doublebonds, in order to prevent polymer scales from adhering topolymerization vessel inner wall surfaces and others, various methodsare known in which the polymerization vessel inner wall surfaces,stirrers and so forth are coated with a polymer scale preventive agent(hereinafter “scale preventive agent”) by one-liquid coating to formcoating films (hereinafter “one-liquid coating method”). As the scalepreventive agent, usable are, e.g., a polar organic compound such as anamine compound, a quinone compound or an aldehyde compound or a dye orpigment (Japanese Patent Publications (kokoku) Nos. 45-30343 and45-30835), a polar organic compound or dye treated with a metal salt(Japanese Patent Publication (kokoku) No. 52-24953, a mixture of anelectron-donating compound and an electron-accepting compound (JapanesePatent Publication (kokoku) No. 53-28347), a condensation reactionproduct of 1-naphthol with formaldehyde (Japanese Pre-examination PatentPublication (kokai) No. 57-164107), a condensation reaction product of aphenol compound with formaldehyde (Japanese Pre-examination PatentPublication (kokai) No. 57-192413), a polyaromatic amine (JapanesePatent Publication (kokoku) No. 59-16561), a self-condensation productof a polyhydric phenol or a self-condensation product of a polyhydricnaphthol (Japanese Pre-examination Patent Publication (kokai) No.54-7487), a condensation reaction product of a ketone resin with aphenol compound (Japanese Pre-examination Patent Publication (kokai) No.62-236804), a condensation reaction product of an aromatic amine with anaromatic nitro compound and a material obtained by making the compoundbasic (Japanese Patent Publication (kokoku) No. 60-30681), and acondensation reaction product of an aromatic amine with a quinonecompound (Japanese Pre-examination Patent Publication (kokai) No.61-7309).

In the case of polymer scale preventive coating films obtained by suchone-liquid coating methods, scales tend to adhere to the vicinity of agas-liquid boundary surface in the polymerization vessel duringpolymerization, or, depending on the composition of a polymerizationreaction mixture, scales tend to adhere to the whole wall surface.Accordingly, to prevent this, it is known to mix in a coating liquidcontaining the scale preventive agent a water-soluble polymeric compoundsuch as an anionic polymeric compound, an amphoteric polymeric compound,a cationic polymeric compound or a hydroxyl-group-containing polymericcompound; an inorganic colloid; or a substance having no affinity formonomers, as exemplified by an inorganic salt such as an alkali metalsalt (hereinafter “scale preventive auxiliary agent”). Theseone-liquidcoating methods are effective for preventing the adhesion ofpolymer scales when monomers having ethylenic double bonds arepolymerized in polymerization vessels.

In instances where no sufficient polymer scale prevention effect can beobtained by the one-liquid coating method, a method of forming coatingfilms by coating two types of coating liquids through two stages(hereinafter “two-liquid two-stage coating method”) is proposed, whichcomprises a) coating a coating liquid containing the scale preventiveagent as described above, to form a first layer, and b) coating furtherthereon a coating liquid containing the above polymer scale preventiveauxiliary agent, to form a second layer (Japanese Pre-examination PatentPublication (kokai)Nos. 3-74404, 2-80403, 2-80402, 2-80401 and 2-47102).

In both the above one-liquid coating method and two-liquid two-stagecoating method for preventing the adhesion of polymer scales, spraycoating is usually used as a coating process in view of productivityincluding operability.

In the one-liquid coating method of coating the scale preventive agentby spray coating, the coating film is formed by a process comprising thefollowing steps 1 to 3.

Step 1: A coating liquid containing the scale preventive agent is coatedon the polymerization vessel inner wall surface and other surfaces withwhich monomers come into contact.

Step 2: The coated surfaces are dried to form a dry film.

Step 3: The surface of the coating film thus formed is washed to removeany excess coating liquid.

In the two-liquid two-stage coating method comprising coating the scalepreventive agent and coating the polymer scale preventive auxiliaryagent both by spray coating, the coating film formation comprising thesame steps 1 to 3 as the above is operated also in the second-stagecoating.

When the above spray coating is used, the surfaces of baffles andstirring blades that face polymerization vessel inner wall surfacesstand within the dead angle from a spray nozzle. Since it is hard forthe coating liquid to reach the surfaces of such portions standing blindor hidden from the spray nozzle, the scale preventive agent can not becoated thereon in the same way as on the surfaces not standing blind.Thus, it is difficult to form a uniform coating film over the surfacesstanding blind and the surfaces not standing blind. If a coating film ina quantity effective enough to prevent the adhesion of polymer scales isintended to be formed also on the blind surfaces, it is inevitable touse a coating liquid containing the scale preventive agent in a largerquantity than that for the other surfaces. It follows that anunnecessarily excess preventive agent is applied on the surfaces notstanding blind. Hence, the coating film thus formed have had an unevencoating thickness and the coating film have had a larger thicknesslocally than is necessary.

The formation of polymer scale preventive coating films by spray coatinghas also had the following problems.

(1) Usually, the coating film comprising the scale preventive agent isformed previously for each polymerization batching. Since it is commonfor the scale preventive agent to have a color, the scale preventiveagent is repeatedly coated as the polymerization is batched repeatedlyin a larger number, so that the coating film may have a large thicknessat some part. The part having such a thick coating film may come off tobecome included into the reaction mixture, or the scale preventive agentmay be coated on polymer scales having already adhered to thepolymerization vessel inner wall surfaces and others and may come offtogether with a part of the scales to mix into the resultantpolymerization products. This may cause colored particles or fish eyesbrought in their formed products or may cause a low product quality suchas a high initial discoloring of formed products, disadvantageously.

(2) As stated above, the effect of preventing scales at the surfacesstanding blind or hidden in the polymerization vessel, standing withinthe dead angle from the spray nozzle, can not be said to be so muchsufficient, considering the scale preventive agent applied in a fairlylarger quantity than that on other surfaces.

(3) The spray coating requires a drying step of drying the coatedsurfaces, and takes a time necessary for forming the coating film of thescale preventive agent. Accordingly, in respect of an improvement ofproductivity, it is sought to shorten the time necessary for forming thecoating film.

As a measure for eliminating the above disadvantages in the spraycoating, a method is proposed in which a coating liquid containing ascale preventive agent is coated using steam as a carrier (hereinafter“wsteam coating”) (Japanese Patent Publication (kokoku) No. 1-5044). Asthe coating liquid in this method, used is a coating liquid comprised ofthe scale preventive agent alone or a coating liquid to which the scalepreventive auxiliary agent is further added.

This steam coating has the following advantages.

(1) A thin and uniform coating film of the scale preventive agent,necessary for preventing the adhesion of scales effectively can beformed using the coating liquid in a small quantity.

(2) The coating film of the scale preventive agent, necessary forachieving the scale prevention effect can be formed using the coatingliquid in a small quantity, also on the portions standing blind orhidden in the polymerization vessel, standing within the dead angle fromthe spray nozzle. Thus, the polymer scale prevention effect can beattained also on these portions.

(3) The drying step is unnecessary in the coating film forming step, sothat the time necessary for forming the coating film of the scalepreventive agent can be shortened.

Incidentally, in the steam coating, the coating liquid and steam aremixed so that the coating liquid is carried by the steam and can beapplied to the polymerization vessel inner wall surfaces and others.Accordingly, the concentration of the scale preventive agent in thecoating liquid is set taking account of the fact that the solution isdiluted with steam. Usually, the concentration of the scale preventiveagent in the coating liquid for steam coating is set 4 to 40 times thatof the one for spray coating, although the amount of a scale preventiveagent necessary in steam coating is approximately equivalent to thatnecessary in spray coating.

In contrast to the advantages, the steam coating has problems on thefollowing points.

(1) Although the steam coating enables uniform coating in apolymerization vessel, the deposition of scale can be preventedinsufficiently around the interface between the gas-liquid phases.

(2) As the result of the insufficient prevention of scale depositionaround the interface between gas-liquid phases, the polymer scaledeposition will grow around the interface with repetition ofpolymerization runs. A part of the grown deposited scale may peel offthe inner surfaces of the polymerization vessel during polymerizationand be incorporated into a polymer product to cause formation offisheyes.

(3) A scale preventive agent is coated on the inner surfaces of apolymerization vessel repeatedly as polymerization runs are repeated.Consequently, the layer of the scale preventive agent become thickergradually. A part of the thick layer of the agent may peel off duringpolymerization and be incorporated into polymer products to causecolored particles. The colored particles will lower anti-initialdiscoloration properties, particularly luminosity index L, of polymerproducts.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a process for producinga polymer by polymerizing a monomer having an ethylenic double bond,which can shorten the time for forming coating films of scale preventiveagents to improve productivity, can improve the effect of preventingscales, can make colored particles less mix into polymer productsobtained by this process, can lessen fish eyes and initial discoloringof formed products and can improve the quality of polymeric products andtheir formed or molded products.

The above subject can be settled by a process for producing a polymer bypolymerizing in a polymerization vessel a monomer having an ethylenicdouble bond, wherein

the polymerization vessel has a polymer scale preventive coating film onits inner wall surfaces and other surfaces with which the monomer comesinto contact during polymerization;

the coating film being formed by coating a first coating liquidcontaining a compound selected from the group consisting of an aromaticcompound having 5 or more conjugated bonds and a heterocyclic compoundhaving 5 or more conjugated bonds and a second coating liquid containingat least one hydrophilic compound selected from the group consisting ofa water-soluble polymeric compound, an inorganic colloid, an inorganicsalt and an acid; the first coating liquid and the second coating liquidbeing simultaneously coated by means of steam as a carrier.

According to the polymerization process of the present invention, thetime for forming coating films of scale preventive agents can beshortened to improve productivity, and also, when monomers having anethylenic double bond are polymerized, polymer scales can be preventedeffectively from adhering to not only wall surfaces at the liquid-phaseportion in the polymerization vessel but also stirrers, baffle surfacesfacing the wall surface, and the vicinity of the boundary surfacebetween the gaseous phase and the liquid phase. Hence, the quality ofpolymer products can be improved and the colored particles can be madevery less mix into polymers, and also formed products obtained byforming the polymers into sheets can be made to have very less fish eyesand also have good anti-initial discoloring.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings,

FIG. 1 schematically illustrates the arrangement in a polymerizationapparatus; and

FIG. 2 schematically illustrates the arrangement in anotherpolymerization apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Scale prevention coating films used in the method of the presentinvention are formed on the surfaces of polymerization vessel innerwalls and so forth. The coating films are formed of a mixture ofcomponents contained in the first coating liquid and second coatingliquid. Here, the components contained in both the coating liquids mayat least react in part to form a reaction product. Hence, stated moreexactly, the coating films are formed of a mixture and/or reactionproduct of the components contained in both the coating liquids.

The scale prevention effect attributable to the present invention isbrought out by cooperation of components of the first coating liquid andsecond coating liquid, and it is difficult to distinguish whichcomponents are contributory. Especially in the coating films formed, theboth components have been made uniform and in some cases have reacted,and it is difficult to state separately what components are contributoryto the effect. In the following description, however, the compoundhaving conjugated bonds of the first coating solution is often calledthe “scale preventive agent” and the hydrophilic compound of the secondcoating solution the “scale preventive auxiliary agent” for the sake ofconvenience.

First Coating Liquid

The aromatic compound and heterocyclic compound used in the firstcoating liquid each have 5 or more conjugated bonds. In the presentspecification, the term “ bonds” is meant to be double bonds and triplebonds, including, e.g., C═C, C≡C, N═N, C═N, C═S and C═O, and the term“conjugated bond” is meant to be a series of bonds wherein each pair ofadjacent bonds are connected to each other through a single bond and allof the bonds have a mutually conjugated relationship with each other.The aromatic compound having 5 or more conjugated bonds and theheterocyclic compound having 5 or more conjugated bonds are hereincalled together generically as “conjugated bond compound” in some cases.The 5 or more bonds are present in the conjugated bond compound may forma single conjugation group or two or more conjugation groups.

Aromatic compound having 5 or more conjugated bonds:

The aromatic compound having 5 or more conjugated bonds may includebenzene derivatives, naphthalene derivatives, polynuclear aromaticcompounds, quinones, non-benzene type aromatic compounds, and aromaticcompound condensation products having a weight-average molecular weight,which term herein means weight-average molecular weight in terms ofpolystyrene as measured by gel permeation chromatography, of 500 ormore.

First, as benzene derivatives, there may be included:

phenols and derivatives thereof, such as 3,7-dihydroxy-10-methylxantheneand hydroxyanthraquinone;

aromatic amines and derivatives thereof, such as quinoline, carbazole,o-phenanthroline, p-phenanthroline, 3,6-diaminoacridine,3-aminophenothiazine, 2-aminophenazine, phenothiazine,2-hydroxy4-methyl-quinoline;

nitro and nitroso derivatives, such as phenazine, phenazine oxide,1-phenylazo-2-naphthol, triphenyldioxadine and 4-nitroxanthone;

aromatic aldehydes, such as benzoflavin;

benzene derivatives having further one substituent other than aldehydegroup, such as 1-hydroxy-2,4-methyl-fluorone, 3-phenylcoumarone, ethylcoumarine-3-carboxylate, 3-acetylcoumarine,5-chloro-3-(4-hydroxyphenyl)anthranyl and 3-nitroacridone;

benzene derivatives having further one substituent other than acylgroup, such as xanthone, 2-benzoylxanthone, xanthene and fluorene;

benzene derivatives and toluene derivatives having three or moredifferent substituents, such as7-acetoxy-8-methoxy-3-(2-nitrophenyl)carbostyryl;

aralkyl compounds, such as 9-benzylacridine; and

diazo compounds and azo compounds, such as 1,1′-azonaphthalene andazoxyphenol.

Next, as naphthalene derivatives, there may be included:

alkyl, alkenyl and phenylnaphthalenes, such as 2-methylnaphthalene,1-ethyl-naphthalene, 2-ethylnaphthalene and 1,2-dimethylnaphthalene;

dinaphthyls, such as 1,1′-dinaphthyl, 1,2′-dinaphthyl and2,2′-dinaphthyl;

naphthylarylmethanes, such as 1-benzylnaphthalene, 2-benzylnaphthalene,1-(α,α-dichlorobenzyl)naphthalene, diphenyl-α-naphthyl-methane,diphenyl-β-naphthylmethane and di-α-naphthylmethane;

naphthylarylethanes, such as 1,2-di-α-naphthylethane and1,2-di-β-naphthylethane;

hydronaphthalenes such as 1,2-dihydronaphthalenes,1,4-dihydronaphthalene and 1,2,3,4-tetrahydronaphthalene;

nitronaphthalenes and derivatives thereof, such asnitromethyl-naphthalene, nitroalkylnaphthalene, nitrophenyl-naphthalene,halo-nitronaphthalene, halo-dinitro-naphthalene, nitrosonaphthalene,diaminonaphthalene, triaminonaphthalene and tetraaminonaphthalene;

halogenated naphthalenes, such as 1-fluoro-naphthalene,1-chloronaphthalene and 1-chloro-3,4-dihydronaphthalene;

naphthylhydroxylamines, naphthylpyrazines and naphthylureas, such asα-naphthylhydroxylamine, β-naphthylthiohydroxyl-amine,N-nitroso-α-naphthylhydroxylamine, α-naphthylhydrazine and1,2-dibenzocarbazole;

naphthalene-based aralkyl compounds, such as dibenzoanthracene,acenaphthene, diphenyl-naphthylchloromethane and nitromethylnaphthalene;

naphthoaldehydes and derivatives thereof, such as α-naphthoaldehyde and2-(2,4-dinitrophenyl)-1-(α-naphthyl)-ethylene;

acetonaphthenes and benzoylnaphthalenes, such as1,2;5,6-dibenzanthracene, 2′-methyl-2,1′-dinaphthyl ketone,2-methyl-1,1′-dinaphthyl ketone and styryl-2-naphthyl ketone.

As the polynuclear aromatic compounds, there may be included:

anthracenes and derivatives thereof, such as anthracene,1,2-dihydroanthracene, 1-chloroanthracene, 1,4-dichloroanthracene,1-nitroanthracene, 9,10-dinitroanthracene, 1-aminoanthracene,2-dimethyl-aminoanthracene, 2-anilinoanthracene,9-methylamino-anthracene, 1,4-diaminoanthracene;

phenanthrenes and derivatives thereof, such as phenanthrene,9,10-dihydrophenanthrene, 1,2,3,4-tetrahydrophenanthrene and1-chlorophenanthrene;

phenanthrenequinones, such as phenanthrene-1,2-quinone andphenanthrene-1,4-quinone; and

polynuclear aromatic compounds and derivatives thereof, such aspentacene, hexacene, benzophenanthrene, benzo[a]anthracene, pyrene andcoronene.

As quinones and derivatives thereof, there may be included:

naphthoquinones and derivatives thereof, such as 1,2-naphthoquinone,3-hydroxy-2,2′-binaphthyl-1,4;3′,4′-diquinone, 5,6-benzoquinoxaline,1,2-benzophenazine, 2-benzoazo-1-naphthol,4-(2,4-dihydroxyphenyl)-1,2-dihydroxynaphthalene,4-(3,4,5-trihydroxyphenyl)-1,2-dihydroxynaphthalene and 1,4-naphthol;and

anthraquinones and derivatives thereof, such as 1,2-anthraquinone,2,3-anthraquinone, 1,4-anthraquinone, alizarin, quinizarin, chrysazin,hystazarin, anthraflavin, isoanthraflavin, anthragallol, purpurin,hydroxyanthrarufin, hydroxychrysazin, hydroxyflavopurpurin, quinazarinand alizarinpentacyanine.

Further, as the non-benzene aromatic compounds, there may be included,for example, azulene, cyclodecapentane, cyclotetradecaheptane,cyclooctadecanonaene, cyclotetracosadodecaene, heptalene, fulvalene,sesquiflulvalene, heptafluvalene and perinaphthene.

The aromatic compound condensation products having a molecular weight of500 or more may suitably be aromatic compound condensation productshaving preferably a weight-average molecular weight of from 500 to70,000, and more preferably from 1,500 to 30,000.

Preferred aromatic compound condensation products include the compoundsbelow, for instance.

Aldehyde Compound/aromatic Hydroxyl Compound Condensation Products

The aldehyde compound/aromatic hydroxyl compound condensation product isa condensation product of an aldehyde compound with an aromatic hydroxylcompound. The use of such aldehyde compound/aromatic hydroxyl compoundcondensation products in scale preventive agents are disclosed in, forexample, Japanese Pre-examination Patent Publication (kokai) No.57-192413, Japanese Patent Publication (kokoku) No. 6-62709, JapanesePre-examination Patent Publication (kokai) No. 57-164107 andWO098/24820.

The aldehyde compounds include, for example, formaldehyde, acetaldehyde,propionaldehyde, butylaldehyde, acrolein, crotonaldehyde, benzaldehyde,furfural, phenylacetaldehyde, 3-phenylpropionaldehyde and2-phenylpropionaldehyde. From industrial and economical viewpoints,formaldehyde and acetaldehyde are advantageous.

The aromatic hydroxyl compounds include, for example, dihydroxybiphenylcompounds, naphthol compounds, phenol compounds, tannins and dimericcompounds of 2,3-dihydroxynaphthalene.

Examples of the dihydroxybiphenyl compounds include2,2′-dihydroxybiphenyl, 2,2′-dihydroxy-5,5′-dimethylbiphenyl,2,2′-dihydroxy-4,4′,5,5′-tetramethylbiphenyl,2,2′-dihydroxy-5,5′-dichlorobiphenyl,2,2′-dihydroxy-5,5′-dichlorohexylbiphenyl and2,2′-dihydroxy-5,5′-di-tert-butylbiphenyl. In particular, from anindustrial viewpoint, 2,2′-dihydroxybiphenyl is preferred.

Examples of the naphthol compounds include 1-naphthol, 2-naphthol,1,3-dihydroxynaphthalene, 1,5-dihydroxynaphthalene,1,7-dihydroxynaphthalene, 6-hydroxy-2-naphthoic acid,2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid and1-hydroxy-8-naphthoic acid.

Examples of the phenol compounds include phenol, cresol, pyrogallol,hydroxyhydroquinone, resorcin, catechol, hydroquinone, bisphenol-A,hydroxybenzoic acid, dihydroxybenzoic acid, 2-hydroxy-5-methoxybenzoicacid and salicylic acid.

Examples of the tannins include tannic acid, Chinese gallotannin,Turkish gallotannin, sumac tannin, quebracho tannin, and tannin ofpersimmon (shibuol).

The dimeric compounds of 2,3-dihydroxynaphthalene include, for example,2,3,2′,3′-tetrahydroxybinaphthyl.

The above condensation product of an aldehyde compound with an aromatichydroxyl compound can be produced by reacting these reactive componentsin a suitable medium in the presence of a catalyst, usually at roomtemperature to 200° C. for 2 to 100 hours, preferably at 30 to 150° C.for 3 to 30 hours. Each of the aromatic hydroxyl compound and thealdehyde compound can be used singly or in combination of two or morekinds.

The medium in which the above condensation reaction is carried outincludes, for example, water; and organic solvents, such as alcohols,ketones and esters. The organic solvents include, for example, alcohols,such as methanol, ethanol and propanol; ketones, such as acetone andmethyl ethyl ketone; and esters, such as methyl acetate and ethylacetate.

The medium in which the above condensation reaction is carried out has apH in the range of usually from 1 to 13, and pH adjusters may be usedwithout any particular limitations.

The catalyst used in the above condensation reaction includes, forexample, acidic catalysts, such as sulfuric acid, hydrochloric acid,perchloric acid, p-toluenesulfonic acid, methanesulfonic acid andtrifluoromethanesulfonic acid; and basic catalysts, such as NaOH, KOHand NH₄OH.

The ratio of the aldehyde to the aromatic hydroxyl compound used whenthe condensation reaction is carried out depends on the types of thealdehyde compound, aromatic hydroxyl compound, solvent and catalystused, the reaction time, the reaction temperature and so forth.Generally, it is preferable to use from 0.1 to 10 mols of the aldehydecompound per mol of the aromatic hydroxyl compound.

Pyrogallol/acetone Condensation Products

The pyrogallol/acetone condensation product is a condensation product ofpyrogallol with acetone, the molar ratio of the pyrogallol to theacetone being in the range of usually from 1/0.1 to 1/10, and themelting point thereof being usually from 100 to 500° C. The meltingpoint increases with an increase in molecular weights. For example,melting points of from 160 to 170° C. correspond to molecular weights offrom 1,450 to 1,650; and melting points of from 200 to 220° C., tomolecular weights of from 2,600 to 4,000. The use of suchpyrogallol/acetone condensation products in scale preventive agents isdisclosed in, for example, Japanese Pre-examination Patent Publication(kokai) No. 4-328104.

The pyrogallol/acetone condensation product can be produced bydissolving pyrogallol in acetone, and condensing them in the presence ofa condensation catalyst. The pyrogallol is used in an amount of usuallyfrom 1 to 100 parts by weight per 100 parts by weight of the acetone. Asthe condensation catalyst, for example, phosphorus oxychloride is used.The reaction may be carried out at room temperature to 100° C.

Polyhydric Phenol Self-condensation Products and Polyhydric NaphtholSelf-condensation Products

Polyhydric phenols are exemplified by catechol, resorcinol,chlororesorcinol, hydroquinone, phloroglucinol and pyrogallol;dihydroxytoluene and dihydroxyxylene; trihydroxytoluene andtrihydroxyxylene; ethyl-, propyl-, butyl- or pentyl-di- ortri-hydroxybenzene; and trihydroxybenzene. Polyhydric naphthols areexemplified by naphthol derivatives, such as 1,3-, 1,4-, 1,5- or1,7-dihydroxynaphthalene. The use of such polyhydric phenolself-condensation products and polyhydric naphthol self-condensationproducts in scale preventive agents is disclosed in, for example,Japanese Pre-examination Patent Publication (kokai) No. 54-7487.

The polyhydric phenol self-condensation product or polyhydric naphtholself-condensation product can be produced by heating polyhydric phenolor polyhydric naphthol in an inert atmosphere, such as nitrogen, argonor the like, at a temperature ranging from 200 to 350° C. for 4 to 100hours. In this reaction, various catalysts may be used, as exemplifiedby zinc chloride, aluminum chloride and sodium hydroxide.

Aromatic Amine Compound Condensation Products

The aromatic amine compound condensation products include, for example;

(1) a self-condensation product of an aromatic amine compound;

(2) a condensation product of an aromatic amine compound with a phenolcompound;

(3) a condensation product of an aromatic amine compound with anaromatic nitro compound; and

(4) a basic product obtained by making basic a condensation product ofan aromatic amine compound with an aromatic nitro compound by the use ofan alkali metal salt or an ammonium compound.

The use of such aromatic amine compound condensation products in scalepreventive agents is disclosed in, for example, Japanese PatentPublication (kokoku) Nos. 59-16561 and 60-30681.

The aromatic amine compounds are exemplified by aniline, o-, m- orp-phenylenediamine, o-, m- or p-aminophenol, o-, m- or p-chloroaniline,p-aminobenzene, 2,4-diaminoazobenzene, p-aminoacetanilide, o-, m- orp-methylaniline, N,N-dimethyl-p-phenylenediamine,4-chloro-o-phenylenediamine, 4-methoxy-o-phenylenediamine,2-amino-4-chlorophenol, 2,3-diaminotoluene, 2,4-diaminophenol, anddiphenylamines such as 4-aminodiphenylamine, 2-aminodiphenylamine,4,4′-diaminodiphenylamine, 4-amino-3′-methoxydiphenylamine and4-amino-4′-hydroxydiphenylamine.

The phenol compounds are specifically exemplified by phenol,hydroquinone, resorcinol, catechol, hydroxyhydroquinone, pyrogallol, o-,m- or p-chlorophenol, o-, m- or p-hydroxybenzoic acid,2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid,2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid,3,5-dihydroxybenzoic acid and 2,5-, 2,6- or 3,5-dihydroxytoluene.

The aromatic nitro compounds are exemplified by nitrobenzene, o-, m- orp-hydroxynitrobenzene, o-, m- or p-nitroanisole, o-, m- orp-nitrophenetole, o-, m- or p-chloronitrobenzene, o-, m- orp-aminonitrobenzene, o-, m- or p-nitrobenzoic acid, o-, m- orp-nitrobenzenesulfonic acid, o-, m- or p-nitroaniline,2-nitro-p-phenylenediamine, 2-amino-4-nitrophenol, 2-amino-5-nitrophenoland 4-amino-2-nitrophenol.

In order to carry out the self-condensation reaction of an aromaticamine compound alone, the condensation reaction of an aromatic aminecompound with a phenol compound and the condensation reaction of anaromatic amine compound with an aromatic nitro compound, a mineral acidand a condensation catalyst are used. The mineral acids are exemplifiedby hydrochloric acid, nitric acid, hydrobromic acid, phosphoric acid andsulfuric acid.

Preferable condensation catalysts are exemplified by permanganic acidand salts thereof, such as permanganic acid and potassium permanganate;chromic acid-related compounds, such as chromium trioxide, potassiumdichromate and sodium chlorochromate; metal nitrates, such as silvernitrate and lead nitrate; halogens, such as iodine and bromine;peroxides, such as hydrogen peroxide, sodium peroxide, benzoyl peroxide,potassium persulfate, ammonium persulfate, peracetic acid, cumenehydroperoxide, perbenzoic acid and p-menthane hydroperoxide; oxygenacids or oxygen acid salts, such as iodic acid, potassium iodate andsodium chlorate; metal salts, such as ferrous chloride, ferric chloride,copper sulfate, cuprous chloride, cupric chloride and lead acetate;ozone; and oxides, such as copper oxide, mercury oxide, cerium oxide,manganese dioxide and osmic acid. It is also effective to use hydrogenperoxide and ferrous chloride in combination.

The self-condensation reaction of an aromatic amine compound alone, thecondensation reaction of an aromatic amine compound with a phenolcompound and the condensation reaction of an aromatic amine compoundwith an aromatic nitro compound may be carried out in the presence of acondensation catalyst at 100 to 350° C. for 2 to 100 hours.

The ratio of an aromatic amine compound to a phenol compound or anaromatic nitro compound, which are used in the condensation reaction ofan aromatic amine compound with a phenol compound and the condensationreaction of an aromatic amine compound with an aromatic nitro compound,depends on the types of the aromatic amine compounds, phenol compoundsand aromatic nitro compounds and catalysts used, the reaction time, thereaction temperature and so forth. Generally, it is preferable to usefrom 0.1 to 10 mols of the phenol compound or the aromatic nitrocompound per mol of the aromatic amine compound.

In order to make basic a condensation product of an aromatic aminecompound with an aromatic nitro compound by the use of an alkali metalsalt or an ammonium compound, for example, 100 parts by weight of thecondensation product of an aromatic amine compound with an aromaticnitro compound is dispersed in water, 10 to 20 parts by weight of analkaline or ammonium compound, such as NaOH, KOH, Na₂CO₃, NH₄OH or(NH₄)₂CO₃ is added thereto, and the mixture obtained is heat treated at90 to 140° C. The alkali or ammonium compound may be used in an amountsufficient to neutralize the mineral acid used at the time of thecondensation reaction.

Quinone Compound Condensation Products

The quinone compound condensation products include, for example, (A) aself-condensation product of a quinone compound, and (B) a condensationproduct of a quinone compound with at least one compound selected fromthe group consisting of an aromatic hydroxyl compound and an aromaticamine compound. The use of such quinone compound condensation productsin scale preventive agents is disclosed in, for example, JapanesePre-examination Patent Publication (kokai) Nos. 5-112603 and 6-56911.

The quinone compounds include, for example, benzoquinones andderivatives thereof, such as o-, m- or p-benzoquinone, tolu-p-quinone,o-xylo-p-quinone, thymoquinone, 2-methoxybenzoquinone, gentisyl quinone,polyporic acid and ubiquinone-n; naphthoquinones and derivativesthereof, such as 6-methyl-1,4-naphthoquinone,2-methyl-1,4-naphthoquinone, α-naphthoquinone, juglone, lawsone,plumbagin, alkannin, echinochrome A, vitamin k₁, vitamin k₂, shikonin,β,β′-dimethyl acrylshikonin, β-hydroxyisovaleroshikonin andteracrylshikonin; anthraquinones and derivatives thereof, such astectoquinone, 3-hydroxy-2-methylanthraquinone, anthraquinone,2-hydroxyanthraquinone, alizarin, xanthopurpurin, rubiadin, munjistin,crysophanic acid, carminic acid, kermesic acid and laccaic acid A; andphenanthrenequinones such as phenanthrenequinone.

The aromatic amine compounds are specifically exemplified by aniline,o-, m- or p-phenylene-diamine, o-, m- or p-chloroaniline, o-, m- orp-methylaniline, N,N-dimethyl-p-phenylenediamine,4-chloro-o-phenylenediamine, 4-methoxy-o-phenylenediamine,2-amino-4-chlorophenol, 2,3-diaminotoluene, 4-amino-2-aminophenol, o-,m- or p-aminophenol, o-, m- or p-aminobenzoic acid, 2,3-, 2,4-, 2,5-,2,6-, 3,4-, 3,5- or 4,6-diaminobenzoic acid, 3- or 4-aminophthalic acid,2-, 4- or 5-aminoisophthalic acid, 4,6-diaminoisophthalic acid, 2,5- or2,6-diaminoterephthalic acid, 3-, 4- or 5-aminosalicylic acid,4-hydroxyanthranilic acid, o-, m- or p-aminobenzenesulfonic acid, 2,3-,2,4-, 2,5-, 2,6-, 3,4- or 3,5-diaminobenzenesulfonic acid,2-amino-1-phenol-4-sulfonic acid and6-amino-4-chloro-1-phenol-2-sulfonic acid, α-naphthylamine,β-naphthylamine, 1,5-diaminonaphthalene, 1-amino-5-hydroxynaphthalene,1,8-diaminonaphthalene, 2,3-diminonaphthalene, 4-amino-1-naphthol,1-amino-5-naphthol, 1,2-naphthylenediamine-7-carboxylic acid,1,5-naphthylenediamine-2-carboxylic acid,1,5-naphthylenediamine-4-carboxylic acid,1,6-naphthylenediamine-4-carboxylic acid,1,8-naphthylenediamine-4-carboxylic acid,1,2-naphthylenediamine-3-sulfonic acid,1,2-naphthylenediamine-4-sulfonic acid,1,2-naphthylenediamine-5-sulfonic acid,1,2-naphthylenediamine-6-sulfonic acid,1,2-naphthylenediamine-7-sulfonic acid,1,3-naphthylenediamine-5-sulfonic acid,1,3-naphthylenediamine-6-sulfonic acid,1,4-naphthylenediamine-2-sulfonic acid,1,4-naphthylenediamine-7-sulfonic acid,1,5-naphthylenediamine-2-sulfonic acid,1,5-naphthylenediamine-4-sulfonic acid,1,5-naphthylenediamine-7-sulfonic acid,1,6-naphthylenediamine-2-sulfonic acid,1,6-naphthylenediamine-4-sulfonic acid,1,6-naphthylenediamine-7-sulfonic acid,1,8-naphthylenediamine-4-sulfonic acid,1,8-naphthylenediamine-3,6-disulfonic acid,1,8-naphthylenediamine-4,5-disulfonic acid,α-amino-β-naphthalenepropionic acid, α-amino-β-naphthalenecarboxylicacid, 2-naphthylamine-1-sulfonic acid, 8-naphthylamine-1-sulfonic acid,5-naphthylamine-1-sulfonic acid, 1-amino-2-naphthol-4-sulfonic acid,2-amino-8-naphthol-6-sulfonic acid (γ-acid),2-amino-5-naphthol-7-sulfonic acid (J-acid) and1-amino-8-naphthol-3,6-disulfonic acid (H-acid), and diphenylamines,such as 4-aminodiphenylamine, 2-aminodiphenylamine,4,4′-diaminodiphenylamine, 4-hydroxydiphenylamine,4-amino-3′-methoxydiphenylamine, 4-amino-4′-hydroxydiphenylamine,4-carboxydiphenylamine, 4-amino-4′-carboxydiphenylamine,4-sulfodiphenylamine and 4- amino-4′-sulfodiphenylamine.

The aromatic hydroxyl compounds are exemplified by phenols andderivatives thereof, such as phenol, hydroquinone, resorcinol, catechol,hydroxyhydroquinone, pyrogallol, o-, m- or p-chlorophenol, o-, m- orp-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoicacid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid,3,5-dihydroxybenzoic acid and 2,5-, 2,6- or 3,5-dihydroxytoluene.

In addition, they are exemplified by naphthols and derivatives thereof,such as α-naphthol, β-naphthol, 1,3-, 1,4-, 1,5-, 2,3-, 2,6- or2,7-dihydroxynaphthalene, 1-hydroxy-2-naphthoic acid and3-hydroxy-2-naphthoic acid.

The self-condensation of a quinone compound or the condensation of aquinone compound with an aromatic hydroxyl compound and/or an aromaticamine compound is carried out in an organic solvent medium, optionallyin the presence of a condensation catalyst. The organic solvent mediumhas a pH within the range of from 1 to 13, preferably from 4 to 10, andpH adjusters may be used without any particular limitations. The pHadjusters used include acidic compounds, for example, phosphoric acid,sulfuric acid, phytic acid and acetic acid; and alkali compounds, forexample, alkaline metal compounds or ammonium compounds, such as LiOH,KOH, NaOH, Na₂CO₃, Na₂SiO₃, Na₂HPO₄ and NH₄OH; and organic aminecompounds, such as ethylenediamine, monoethanolamine andtriethanolamine.

As the medium for the condensation reaction, organic solvents asexemplified by alcohols, ketones and esters, or mixed solvents of waterand organic solvents miscible with water are preferred. Usable organicsolvents miscible with water include, for example, alcohols, such asmethanol, ethanol and propanol; ketones, such as acetone and methylethyl ketone; and esters, such as methyl acetate and ethyl acetate.

The condensation catalyst may be optionally used which is exemplified byazo catalysts such as α,α′-azobisisobutylonitrile andα,α′-azobis-2,4-dimethylvaleronitrile; elementary or molecular singlehalogens, such as iodine, bromine and chlorine; peroxides, such ashydrogen peroxide, sodium peroxide, benzoyl peroxide, potassiumpersulfate, ammonium persulfate, peracetic acid, cumene hydroperoxide,perbenzoic acid and p-menthane hydroperoxide; oxygen acids or oxygenacid salts, such as iodic acid, periodic acid, potassium periodate andsodium perchlorate. Incidentally, since the quinone compound acts as acondensation catalyst, the condensation reaction takes place even in theabsence of a condensation catalyst.

The condensation reaction may be generally carried out at roomtemperature to 200° C. for 0.5 to 100 hours.

When (a) a quinone compound and (b) an aromatic hydroxyl compound and/oran aromatic amine compound are condensed, the proportion of bothreactive components used depends on the types of the aromatic aminecompounds, quinone compounds and aromatic hydroxyl compounds, thereaction temperature and the reaction time. It is preferable to use from0.01 to 10.0 mols of the component (b) per mol of the component (a).

Sulfide Compounds of Aromatic Hydroxyl Compounds

Sulfide compounds of aromatic hydroxyl compounds refer to condensationproducts of aromatic hydroxyl compounds with sulfur chlorides such assulfur monochloride and sulfur dichloride. Use of such sulfide compoundsof aromatic hydroxyl compounds in the scale preventive agent isdisclosed in, e.g., Japanese Pre-examination Patent Publication (kokai)Nos. 4-311702, 4-339801, 5-155905 and 6-9711.

The aromatic hydroxyl compounds may include aromatic hydroxyl compoundsof naphthol compounds described above, phenol compounds and the like.

To obtain the sulfide compounds, various methods are available. Forexample, a method is available in which the above phenols and sulfurchlorides such as sulfur monochloride and sulfur dichloride aresubjected to condensation reaction. This reaction is carried out in anorganic solvent inert to sulfur chlorides, in which a polyhydric phenolhas been dissolved. Such an organic solvent may include, e.g., aromatichydrocarbons such as toluene, xylene and chlorobenzene, and ethylenedichloride, chloroform and ethyl acetate. The phenol and the sulfurchloride may be in such a ratio that the latter is from about 0.5 to 2mols, and preferably from about 0.9 to 1.2 mols, per mole of the former.The reaction may be carried out at a temperature of from about 50° C. toabout 150° C. Hydrogen chloride formed as a by-product may bevolatilized, or, in a closed system, a dehydrochlorinating agent such astriethylene-amine may be used. After the reaction has been completed, inan instance where the reaction product stand dissolved in the solvent,the solvent may be removed by evaporation to take out the reactionproduct. In an instance where the reaction product stand deposited,solid-liquid separating operation such as filtration may be carried outto take out the reaction product.

As another method for obtaining the sulfide compound, a method isavailable in which a polyhydric phenol and a small amount of an alkalihydroxide are heated and melted, sulfur powder is added thereto littleby little and further the temperature is raised to about 150° C. toabout 200° C., where the reaction is carried out while releasing to theoutside of the system the hydrogen sulfide being formed, the reactionmixture is cooled and thereafter dissolved in the solvent describedlater, followed by filtration to collect the insoluble matter, which isthen neutralized with a dilute acid, and the aqueous phase is removed toobtain the compound in the form of a solution.

Heterocyclic compound having 5 or more conjugated bonds:

The heterocyclic compounds having 5 or more conjugated bonds include,for example, oxygen-containing heterocyclic compounds,nitrogen-containing heterocyclic compounds, sulfur-containingheterocyclic compounds, dicyclic compounds having a nitrogen atompossessed in common by the two rings, and alkaroids.

First, as the oxygen-containing heterocyclic compounds, there may beincluded:

benzofuran, isobenzofuran, dibenzofuran and derivatives thereof, such asfurano-[2′,3′-7,8]flavone, 9-phenylanthracene,o-hydroxymethyltriphenylcarbinol, 3,3′-diphenylphthalide, rubrene,α-sorinine and phenazone;

pyran derivatives and pyrone derivatives, such as2-p-hydroxyphenyl-4,6-diphenylpyrylium ferrichloride, anhydrobase,benzopyran and 6-phenylcoumarin;

chromenol derivatives and chromene derivatives, such as6-methyl-2,3-diphenylchromone,6-methyl-2,3-diphenyl-4-(p-tolyl)-1,4-benzopyran-4-ol, chromanol,γ-chromene, hydroxychmarone, chromene, cyanizine chloride, fisetin,chrysinidine, apigenidin and rotoflavinidine;

flavone, flavonol and isoflavon derivatives, such as flavonol, flavone,fukugetin;

coumarin, its derivatives, isocoumarin and its derivatives, such as7-hydroxy-3,4-benzocoumarin, dicoumarol, angelicin, psoralen, bergapten,bergaptol, xanthotoxin, xanthotoxal, isopimpinellin, pimpinellin,oroselol, oroselone, peucedanin, hydroxypeucedanin, ostruthol,medakenine, nodakenetin, seselin, xanthyletin, xanthoxyletin; and

xanthone and related compounds; such as dixanthylene, 9-phenylxanthene,isoxanthone, 1,2,7,8-dibenzoxanthene, 3,9-diphenylxanthene,9,9-diphenylxanthene, and the like.

Next, the nitrogen-containing heterocyclic compounds may include:

indoles, such as indolo[3,2-c]quinoline, indolo[1,2-c]quinazoline,2-(1-naphthyl)-3-triphenylmethylindole,2-(2-naphthyl)-3-triphenylmethylindole, 3,3′-diindolyl and3,2′-diindolyl;

oxoderivatives of indole, such as 3-(4-ethoxy-1-naphthyl)hydroxyindoleand indophenine;

carbazoles, such as 1-phenyl-1,2,3-benzotriazole, 2,2′-diaminodiphenyl,1,1′-dicarbazole;

porphyrins, such as porphyrazine, magnesium octamethyltetraazaporphyrin,azadipyromethine, diazacoproporphyrin, porphine andmesotetraphenylporphyrin;

oxazoles, such as phenanthrooxazole;

thiazoles, such as α-naphthothiazole, β-naphthothiazole,naphtho[1,2]thiazole, 2-methyl[1,2]thiazole,2-phenylnaphtho[1,2]thiazole, 2-methylnaphtho[2,1]-thiazole,2-hydroxynaphtho[2,1]thiazole, 2-aminonaphtho[1,2]thiazole and2-mercaptonaphtho[1,2]-thiazole;

oxadiazoles, such as naphtho[1,2]furazane;

quinoline and related compounds, such as quinoline, quinaldine,quinaldine-N-oxide, ethylquinoline, 2-phenylquinoline,3-methylquinoline, 4-phenylquinoline, 6-methylquinoline and2,4-dimethylquinoline;

isoquinoline and related compounds, such as 1-methylisoquinoline,1-phenylisoquinoline, 4-phenylisoquinoline, 1,1′-biisoquinoline and5,5′-biisoquinoline;

acridine and related compounds, such as acridine, 1-methylacridine,9-phenylacridine, 9-(3-pyridinyl)acridine, 2-acridinol,acridine-3,6-diol, 4-methoxyacridine, 9-phenoxyacridine,1-nitroacridine, 4-aminoacridine, 1-aminoacridine,9-phenylaminoacridine, 9-hydroxyacridine and3,6-diamino-4,5-dimethylacridine;

phenanthridines, such as 3,4-benzoquinoline, 6-methylphenanthridine,6-aminomethylphenanthridine and 6-phenylphenanthridine;

anthrazolines, such as pyrido[2,3-g]quinoline,2,7-diphenyl[2,3-g]quinoline, 2,8-diphenylpyrido[3,2-g]-quinoline;

phenanthroline and related compounds, such as 1,7-phenanthroline and1,10-phenanthroline;

pyridoindoles, such as 1,9-pyridoindole, 2,9-pyridoindole and4,9-pyridoindole;

naphthylidine and related compounds, such as 1,5-naphthylidine,1,7-naphthylidine, 1,8-naphthylidine, 3-amino-1,5-naphthylidine,2-amino-1,5-naphthylidine and 2-hydroxy-1,7-naphthylidine;

oxazine and related compounds such as phenoxazinone and resazurin;

thiazine and related compounds, such as phenothiazine,nitrophenothiazine, 4-amino-4′-anilinodiphenyl disulfide,2-chloro-10-(3-dimethylaminopropyl)phenothiazine,10-[1-methyl-3-piperidylmethyl)phenothiazine and2-acetyl-10-(3-dimethylaminopropyl)phenothiazine;

pyridazine and related compounds, such as cinnoline, 3-methylcinnoline,4-chlorocinnoline, 3-bromocinnoline, 4-cinnolinol, 4-aminocinnoline,phthalazine, 4-ethyl-2-phenylphthalazinone and phthalazine thiol;

pyrimidine and related compounds, such as sulfadiazine, sulfisomidine,pteridine, 2,4-pterine diol, 2-amino-6-methyl-4-pteridinol,xanthopterine, quinazoline, 2,4-dichloroquinazoline and2,3-diphenyl-4-quinazoline;

pyrazine related compounds, such as quinoxaline and 2-methylquinoxaline;

tri- and tetra-hetero six-membered cyclic compounds, such as1,2,4-benzotriazine and 1,2,4-benzotriazine-3-ol;

Further, the sulfur-containing heterocyclic compounds may include:

fused thiophene compounds, such as dihydronaphtho[2,1-b]-thianaphthene,1,3-diphenylisothianaphthene and dibenzothiophene;

five-membered monocyclic compounds containing 2 hetero atoms, such as3,4-dihydronaphtho-2,1-trithione, thiaflavone, thiacoumarin,thiaxanthene, thiaxanthohydrol, thiaxanthone, Milacil D, andbisthiaxanthylene;

six-membered cyclic compound having two or more hetero atoms, such asthianthrene, 2,7-dimethylthianthrene, 1-thianthrenyl lithium,1-chlorothianthrene and phenoxathine.

Further, other useful compounds may include:

dicyclic compounds having a nitrogen atom possessed in common by the tworings, such as 2:3-benzopyrrocoline,1,5,8-trimethyl-2:3-benzopyrrocoline and1-ethyl-5,8-dimethyl-2:3-benzopyrrocoline; and

alkaroids, such as casimiroin, 2-penthylquinoline,4-hydroxy-2-pentylquinoline and 4-methoxy-2-pentylquinoline.

Of the conjugated bond compounds, it is preferable to use those whichare condensation products of aromatic compounds and have aweight-average molecular weight of 500 or more.

Of the condensation products of aromatic compounds, aldehydecompound/aromatic hydroxyl compound condensation products and quinonecompound condensation products are particularly preferred.

The first coating liquid is prepared by dissolving the conjugated bondcompound in a proper solvent. The solvent includes, for example, water;alcohol solvents, such as methanol, ethanol, propanol, butanol,2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1-butanol,2-methyl-2-butanol and 2-pentanol; ketone solvents, such as acetone,methyl ethyl ketone and methyl isobutyl ketone; ester solvents, such asmethyl formate, ethyl formate, methyl acetate, ethyl acetate and methylacetoacetate; ether solvents, such as 4-methyldioxolane and ethyleneglycol diethyl ether; furans; and non-protonic solvents, such asdimethylformamide, dimethyl sulfoxide and acetonitrile. The solvents maybe appropriately used singly or as a mixed solvent of two or morethereof.

Among the above solvents, preferred are water and a mixed solvent ofwater and an organic solvent miscible with water. Among the aboveorganic solvents, organic solvents miscible with water include alcoholsolvents, such as methanol, ethanol and propanol; ketone solvents, suchas acetone and methyl ethyl ketone; and ester solvents, such as methylacetate and ethyl acetate. Particularly, it is preferred that alcoholsolvents are used. In the case where a mixed solvent of water and anorganic solvent miscible with water is used, the organic solvent ispreferably contained in such an amount that there is no danger ofinflammation, evaporation and the like and there is no problem on safetyin handling, for example, on toxicity. Specifically, the amount ispreferably 50% by weight or less, more preferably 30% by weight or less.

The pH of the first coating liquid is selected appropriately dependingon the kind of the conjugated bond compound. For example, forpyrogallol/acetone condensation products, polyhydric phenolself-condensation products and polyhydric naphthol self-condensationproducts, a pH of 2.0 to 6.5 is preferred. For this pH adjusters usedfor adjustment of the pH include, for example, hydrochloric acid,sufuric acid, phosphoric acid, pyrophosphoric acid and nitric acid. Forthe condensation products of aldehyde compound/aromatic hydroxylcompound, condensation products of an aromatic amine compound, andcondensation products of a quinone compound, a pH of 7.5 to 13.5 ispreferred, and a pH of 8.0 to 12.5 is more preferred. For that case,alkaline compounds used for pH adjustment include, for example, alkalimetal compounds or ammonium compounds, such as LiOH, NaOH, KOH, Na₂CO₃,Na₂HPO₄ and NH₄OH; and organic amine compounds, such as ethylenediamine,monoethanolamine, diethanolamine and triethanolamine.

The conjugated bond compound in the first coating liquid may preferablybe in a concentration ranging from 1.0 to 25.0% by weight, morepreferably from 2.5 to 15.0% by weight, and still more preferably from 4to 10% by weight. If they are in too low a concentration, a difficultymay occur such that the steam must be used in a large quantity in orderto form the first layer in an effective quantity. If they are in toohigh a concentration, the coating liquid may become unstable to cause aprecipitate during storage in a storage tank, or coating solution feedlines and coating nozzles may clog with precipitates of deposits, makingit difficult to coat the coating solution. As the result, this causes alowering of the scale prevention effect.

To the first coating liquid, an anticorrosive agent, an antifungal agentand so forth may optionally be added as long as the effect of thepresent invention is not damaged.

Second Coating Liquid

As the second coating liquid, a coating liquid containing at least onehydrophilic compound selected from the group consisting of awater-soluble polymeric compound, an inorganic colloid, an inorganicsalt and an acid is used.

Water-soluble Polymeric Compound

The water-soluble polymeric compound includes, for example,water-soluble hydroxyl group-containing polymeric compounds,water-soluble amphoteric polymeric compounds, water-soluble anionicpolymeric compounds and water-soluble cationic polymeric compounds.

The water-soluble hydroxyl group-containing polymeric compounds include,for example, starches such as amylose, amylopectin, dextrin and oxidizedstarch; animal viscous liquid materials such as chitin; cellulosederivatives such as methyl cellulose, glycol cellulose, ethyl methylcellulose, hydroxyethyl cellulose, and hydroxyethyl methyl cellulose;hemicelluloses such as xylan, mannan, arabogalactan, galactan, andaraban; lignins such as alcohol lignin, dioxane lignin, phenol lignin,hydrotropic lignin, mercaptolignine, alkali lignin, thioalkali lignin,acid lignin, cuproxam lignin, and periodate lignin; and partiallysaponified polyvinyl alcohols and polyvinyl alcohols. Among these,preferred are amylopectin, dextrin, methyl cellulose, glycol cellulose,mannan, galactan, alcohol lignin, dioxane lignin, alkali lignin, andacid lignin. The water-soluble amphoteric polymeric compounds include,for example, glue, gelatin, casein, albumin, ribonucleic acids,deoxyribonucleic acids, and chitosan. The water-soluble anionicpolymeric compounds include, for example, anionic polymeric compoundshaving a carboxyl group or sulfonic acid group in their side chain asexemplified by sulfomethylated compounds of polacrylamide, polyacrylicacid, alginic acid, an acrylamide/vinylsulfonic acid copolymer,polymethacrylic acid and poystyrenesulfonic acid, carboxymethyl starch,pectic acid, pectinic acid, protopectinic acid, carragheenin, hyaluronicacid, chondroitin sulfuric acid, heparin, keratosulfuric acid,thioglycollic acid, lignin sulfonic acid, styrene-maleic anhydridecopolymers, acrylic acid-maleic anhydride copolymers, and carboxymethylcellulose. The water-soluble cationic polymeric compounds includecationic polymeric electrolytes having nitrogen atoms on the sidechains, the nitrogen atoms having positive charges, as exemplified bypolyethylene-imine, polyvinyl amine, polyacrylamide, anN-vinyl-2-pyrrolidone/acrylamide copolymer, a cyclized polymer ofdimethyldiamylammonium chloride, a cyclized polymer ofdimethyldiethylammonium bromide, a cyclized polymer of diallylaminehydrochloride, a cyclized copolymer of dimethyldiallylammonium chloridewith sulfur dioxide, polyvinyl pyridine, polyvinyl pyrrolidone,polyvinyl carbazole, polyvinyl imidazoline, polydimethylaminoethylacrylate, polydiethylaminoethyl acrylate, polydiethylaminoethylmethacrylate, and derivatives or modified products of any of thesepolymeric compounds, as exemplified by partially cross-linked products,copolymers, graft copolymers, and these polymeric compounds into which afunctional group such as —OH, —NH₂, —COOH or —SO₃H has been introduced.

Of the water-soluble polymeric compounds exemplified above, preferredare methyl cellulose, hydroxyethyl cellulose, hydroxyethylmethylcellulose, polyvinyl alcohol, partially saponified polyvinyl alcohol,glue, casein, gelatin, chitosan, polyacrylic acid, alginic acid,polymethacrylic acid, pectic acid, carragheenin, hyaluroic acid,carboxymethyl cellulose, polyvinyl pyrrolidone and a styrene-maleicanhydride copolymer.

Inorganic Colloid

The inorganic colloids include, for example, colloids of oxides orhydroxides of metals selected from aluminum, thorium, titanium,zirconium, antimony, tin, iron and so forth; colloids of tungstic acid,vanadium pentoxide, selenium, sulfur, silica, gold or silver; and silveriodide sol. Among them, preferred are colloids of oxides or hydroxidesof metals selected from aluminum, titanium, zirconium, tin and iron; andcolloidal silica. These inorganic colloids may be those obtained by anyproduction processes on which there are no particulate limitations. Forexample, particulate colloids produced by a dispersion process usingwater as a dispersion medium or an agglomeration process are available.The colloidal particles have a size of preferably 1 to 500 nm.

Inorganic Salt

The inorganic salts include, for example, alkaline metal silicates andinorganic salts of alkaline-earth metals.

The alkaline metal silicate include, for example, metasilicates(M₂SiO₃), orthosilicates (M₄SiO₄), disilicates (M₂Si₂O₃), trisilicates(M₃Si₃O₇) and sesquisilicates (M₄Si₃O₁₀) wherein in these formulae, Mrepresents an alkaline metal, such as lithium, sodium or potassium, ofalkaline metals; and water glass.

The inorganic salts of alkaline earth metals include, e.g., silicates,carbonates, phosphates, sulfates, nitrates, borates, acetates,hydroxides, oxides or halides of alkaline earth metals such asmagnesium, calcium and barium. Of these alkaline earth metal compounds,particularly preferred are magnesium carbonate, calcium carbonate,magnesium phosphate, calcium phosphate, calcium pyrophosphate, calciumdihydrogenpyrophosphate, barium phosphate, calcium sulfate, calciumborate, magnesium hydroxide, calcium hydroxide, barium hydroxide,magnesium chloride and calcium chloride.

Acid

The acid may include inorganic acids such as phosphoric acid,pyrophosphoric acid, polyphosphoric acid, phosphomolybdenic acid,silicomolybdenic acid, phosphotungstic acid, silicotungstic acid,molybdic acid and tungstic acid; and organic acids such as terephthalicacid, 1,12-dodecanedicarboxylic acid, 1-dodecanedisulfonic acid, benzoicacid, lauric acid, sulfanilic acid, p-styrene sulfonic acid, propionicacid, salicylic acid, copper phthalocyanine tetrasulfonic acid, urocanicacid, L-asciorbic acid, D-isoasciorbic acid, chlorogenic acid, caffeicacid, p-toluenesulfonic acid, sorbic acid, β-naphthoquinone 4-sulfonicacid, phytic acid and tannic acid.

Of the above hydrophilic compounds, water-soluble polymeric compounds,inorganic colloids and inorganic salts are preferred, and water-solublepolymeric compounds are particularly preferred.

The second coating liquid is prepared by dissolving at least oneselected from the above hydrophilic compounds in a suitable solvent. Asthe solvent, water or a mixed solvent of water and a hydrophilic organicsolvent having an affinity for water may be used. Of the above solvents,the hydrophilic organic solvent may include alcohol type solvents suchas methanol, ethanol and propanol; ketone type solvents such as acetoneand methyl ethyl ketone; and ester type solvents such as methyl acetateand ethyl acetate. In addition, of the above solvents, it is preferableto use alcohol type solvents. In the case when the mixed solvent ofwater and the hydrophilic organic solvent is used, the hydrophilicorganic solvent may preferably be used in such a content that there isno danger of combustion or explosion and there is no problem on thesafety in handling such as toxicity. Stated specifically, thehydrophilic organic solvent may preferably be in a content of 50% byweight or less, and more preferably 30% by weight or less. Preferably,all of the solutes are completely dissolved and colloidal particles arecompletely uniformly dispersed in a solvent to form the second coatingliquid in a uniform solution.

In the second coating solution, a pH adjuster such as NaOH orethylenediamine may also optionally be used. An anticorrosive agent, anantifungal agent and so forth may further be added as long as the effectof the present invention is not damaged.

The hydrophilic compound in the second coating liquid may preferably bein a concentration ranging from 0.01 to 20% by weight, more preferablyfrom 0.1 to 15% by weight.

Carrier Steam

According to the process of the present invention, the coating film isformed by applying the first and second coating liquids simultaneouslyon the polymerization vessel inner wall by means of steam as a carrier.The steam used may be steam usually available or superheated steam, andmay preferably be steam having a pressure of from 2 to 35 kgf/cm²·G(0.20 to 3.43 MPa·Gauge), and more preferably one having a pressure offrom 2.8 to 20 kgf/cm²·G (0.27 to 1.96 MPa·Gauge). The steam maypreferably have a temperature of from 120 to 260° C., and morepreferably from 130 to 200° C.

The pressure and temperature of the steam described above are the valuesmeasured before the mixing of the steam with the coating solutions, forexample, in the interior of a steam feed line 6 as shown in FIG. 1described below.

Formation of Coating Film

The coating film formed by the method of the present invention will bedescribed with reference to a coating apparatus shown in FIG. 1, whichillustrates the arrangement in a polymerization apparatus.

Step 1. (Pre-heating of Polymerization Vessel Inner Wall Surfaces andOthers by Steam)

Hot water or the like is passed through a jacket 2 attached to apolymerization vessel 1 to pre-heat the polymerization vessel inner wallsurfaces to a temperature of 50° C. or above (preferably from 50 to 95°C.). At the upper part of this polymerization vessel, a coating ring 4is provided which is formed of a ring-shaped pipe and has upward nozzles3 b and downward nozzles 3 a. To the coating ring 4, a line 5 isconnected through which the steam and the coating liquid are fed fromthe outside of the polymerization vessel 1. To line 5 are connected asteam feed line 6, the first coating liquid feed line 7 and the secondcoating liquid feed line 8 through the respective valves. If necessary,the steam (usual steam or superheated steam) may be blown into thevessel from the coating nozzles 3 a and 3 b of this coating ring 4 topre-heat also baffles (not shown) and stirring blades (not shown). Inthis apparatus, the steam is fed to the coating ring 4 from a steamfeeder 9 via a flowmeter 10 through lines 6 and 5.

Step 2. (Coating)

The steam is fed to the coating ring 4, and the first coating liquidheld in a first coating liquid tank 11 is fed to the coating ring 4through lines 7 and 5 by means of a pump 12 or an aspirator valve (notshown). P denotes a pressure gauge. Substantially at the same time, thesecond coating liquid held in a second coating liquid tank 13 is fedlikewise to the coating ring 4 through lines 8 and 5 by means of a pump14.

The first and second coating liquids are carried by the steam and is, inthe state of mist, applied to and coated on polymerization vessel innerwall surfaces and surfaces with which polymers come into contact duringpolymerization, such as baffle surfaces and stirring blade surfaces.Simultaneously with this coating, a mixture and/or reaction product ofthe first and second coating liquids coated on these surfaces is dried(simultaneous drying), so that the coating film is formed. Hence, it isunnecessary to make any particular operation for the drying.

The steam (G) and the total of the first and second coating liquids (L)may preferably be in a mixing ratio (L/G) of from 0.005 to 0.8, and morepreferably from 0.01 to 0.2, as flow rate ratio on the basis of weight.

The first coating liquid (L1) and the second coating liquid (L2) may bemixed in a proportion (L1/L2) appropriately adjusted in accordance withthe concentration of the respective coating liquids. Their proportionmay preferably be so adjusted that the conjugated--bond-containingcompound in the first coating liquid and the hydrophilic compound in thesecond coating liquid are in a weight ratio ranging from 0.01 to 100,and more preferably ranging from 0.20 to 30. In accordance with theconcentration of the both coating liquids, the flow rate ratio(weight-based) of the L1 and L2 may preferably be so adjusted to 0.1 to10.0, and more preferably 0.2 to 5.0, that such a solid matter componentratio can be attained.

Step 3. (Water washing)

After the feeding of the steam and the coating liquid are stopped, theinside of the polymerization vessel is washed with cleaning water heldin a water tank 15. The cleaning water is fed into the polymerizationvessel 1 from nozzles 18 through a line 17 by means of a pump 16.However, water washing is unnecessary if the coating liquid does not soaffect the product quality.

The coating film thus formed may preferably have a dried coating weightof from 0.001 to 5 g/m², and more preferably from 0.001 to 2 g/m².

Polymerization

The process of the present invention is applied to the polymerization ofa monomer having an ethylenically unsaturated double bond. Examples ofthe monomer include vinyl halides such as vinyl chloride; vinyl esterssuch as vinyl acetate andvinyl propionate; acrylic acid, methacrylicacid and their esters or salts; maleic acid, fumaric acid and theiresters or anhydrides; diene monomers such as butadiene, chloroprene andisoprene; styrene; acrylonitrile; vinylidene halides; and vinyl ether.

Examples particularly suitable for practicing the process of the presentinvention include the production of polymers of vinyl halides, such asvinyl chloride, vinylidene halides, or a monomeric mixture comprisedprimarily of them by suspension polymerization or emulsionpolymerization in an aqueous medium. The coating film formed by theprocess of the present invention has a high durability even formonomers, such as α-methylstyrene, acrylic acid esters, acrylonitrileand vinyl acetate, which have a high solvency power for the conventionalcoating film, so that the process can be carried out suitably even forthe production of polymer beads and latex comprised of polystyrene,polymethacrylate, polyacrylonitrile, etc.; the production of syntheticrubbers such as SBR, NBR, CR, IR, IIR, etc.(these synthetic rubbers aregenerally produced by emulsion polymerization); and the production ofABS resin.

In the polymerization of one or more of these monomers, an object ofpreventing scale can be effectively accomplished irrespective ofpolymerization types, such as suspension polymerization, emulsionpolymerization, bulk polymerization and solution polymerization, even inthe presence of any of additives such as emulsifiers, stabilizers,lubricants, plasticizers, pH adjusters and chain transfer agents. Forexample, in the case of suspension polymerization or emulsionpolymerization of a vinyl monomer, various additives are optionallyadded, as required. The additives include, for example, suspendingagents such as partially saponified polyvinyl alcohol and methylcellulose; anionic emulsifiers such as sodium lauryl sulfate; nonionicemulsifiers such as sorbitan monolaurate and polyoxyethylene alkylether; stabilizers such as tribasic lead sulfate, calcium stearate,dibutyltin dilaurate and dioctyltin mercaptide; chain transfer agentssuch as trichloroethylene and mercaptans; and pH adjusters. According tothe present process, deposition of scale is effectively prevented in thepresence of any of the additives above.

The remarkable polymer scale deposition preventive effect of theinvention is exhibited without being affected by the kind ofpolymerization catalysts even when any of catalysts is used.Specifically, the catalysts include, for example, t-butylperoxyneodecanoate, bis(2-ethylhexyl)peroxydicarbonate,3,5,5-trimethylhexanoyl peroxide, α-cumylperoxyneodecanoate,cumenehydroperoxide, cyclohexanone peroxide, t-butyl peroxypivarate,bis(2-ethoxyethyl)peroxydicarbonate, benzoyl peroxide,diisopropylbenzene hydroperoxide, lauroyl peroxide, 2,4-dichlorobenzoylperoxide, diisopropyl peroxydicarbonate, α,α′-azobisisobutylonitrile,α,α′-azobis-2,4-dimethylvaleronitrile, di-2-ethylhexyldiperoxyisophthalate, potassium persulfate and ammonium persulfate.

Other conditions for polymerization may be those which areconventionally used, and there are no limitations unless the effects ofthe present invention are impaired. In the following, taking the casesof suspension polymerization, solution polymerization and bulkpolymerization as examples, typical conditions of polymerization will bedescribed.

First, in the suspension polymerization, water and a dispersant arecharged into a polymerization vessel, and then a polymerizationinitiator is charged therein. Subsequently, the polymerization vessel isevacuated to reduce the initial pressure to a value of 0.1 to 760 mmHg(0.01 to 101 kPa), and a monomer or monomers are then charged, whereuponthe internal pressure takes usually a value of 0.5 to 30 kgf/cm²·G (150to 3,040 kPa). Thereafter, polymerization is carried out at a reactiontemperature of 30 to 150° C. During the polymerization, one or morematerials selected from water, a dispersant and a polymerizationinitiator are, optionally, added. Reaction temperature during thepolymerization is different depending on the kind of a monomer to bepolymerized. For example, in the case of polymerizing vinyl chloride,polymerization is carried out at 30 to 80° C., while in the case ofpolymerizing styrene, polymerization is carried out at 50 to 150° C. Thepolymerization may be judged to be completed when the pressure insidethe polymerization vessel has dropped to a value of 0 to 7 kgf/cm²·G(100 to 790 kPa) or when there has been observed substantially nodifference between the inlet temperature and outlet temperature of acooling water flowing into and out of a jacket providedcircumferentially of the polymerization vessel (i.e., when liberation ofheat due to the polymerization reaction has subsided). The amounts ofthe water, dispersant and polymerization initiator are generally 20 to500 parts by weight, 0.01 to 30 parts by weight, and 0.01 to 5 parts byweight, respectively, per 100 parts by weight of the monomer.

In solution polymerization, an organic solvent, such as toluene, xyleneand pyridine, is used as the polymerization medium, in place of water.If necessary, a dispersant may be used. The other conditions forpolymerization are generally the same as those described for suspensionpolymerization.

In bulk polymerization, after a polymerization vessel is evacuated to apressure of about 0.01 to 760 mmHg (0.001 to 101 kPa), a monomer and apolymerization initiator are charged into the polymerization vessel, andthen polymerization is carried out at a reaction temperature of −10 to250° C. For example, the reaction temperature is 30 to 80° C. for thepolymerization of vinyl chloride, and is 50 to 150° C. for thepolymerization of styrene.

EXAMPLES

The present invention will now be described below in greater detail bygiving Examples. In the following, “part(s)” refers to “part(s) byweight”. In tables, “auxlliary agents” refers to “polymer scalepreventive auxiliary agent”.

Production of Condensation Products

In the following Production Examples, the weight-average molecularweight of each condensation product obtained was measured in thefollowing way.

Measurement of Weight-average Molecular Weight

Weight-average molecular weight in terms of polystyrene was measured bygel permeation chromatography (GPC) under the following measurementconditions.

Columns:

Guard column:

Trade name: Shim-pack GPC-800DP, manufactured by Shimadzu Corporation.

Analytical columns:

Trade name: shim-pack GPC-803D, 802D, manufactured by ShimadzuCorporation.

Mobile phase: 10 mM LiBr/DMF

Flow rate: 1.0 ml/min

Detector: RI

Temperature: 60° C.

Production Example 1 Production of Condensation Product No. 1

Into a pressure-resistant reaction vessel, 30,000 mols (960 kg) ofmethanol, 100 mols (15.8 kg) of 1,8-diaminonaphthalene, 50 mols (5.4 kg)of p-benzoquinone and 250 mols (31.5 kg) of pyrogallol were charged, andthe temperature was raised to 70° C. with stirring. After the reactionwas carried out at 70° C. for 10 hours, the reaction mixture was cooledto obtain a methanol solution of a condensation product (CondensationProduct No. 1). The Condensation Product No. 1 had a weight-averagemolecular weight of 3,500.

Production Example 2 Production of Condensation Product No. 2

With reference to Production Example 3 disclosed in Japanese PatentPublication (kokoku) No. 6-62709, a scale preventive agent was produced.

Into apressure-resistant reaction vessel, 30 mols (5.59 kg) of2,2′-dihydroxybiphenyl, 30 mols (0.948 kg) of paraformaldehyde with apurity of 95%, 0.19 kg of paratoluenesulfonic acid and 10 liters ofethylene glycol dimethyl ether were charged, and the temperature wasraised to 130° C. with stirring. After the reaction was carried out at130° C. for 17 hours, the reaction mixture was cooled to 50° C. and thenput into 50 liters of water. The resin separated by putting said mixtureinto water was filtered off and then washed with water, followed bydrying to obtain 5.1 kg of a 2,2′-dihydroxybiphenyl-formaldehydecondensation resin (Condensation Product No. 2). The CondensationProduct No. 2 had a weight-average molecular weight of 5,400.

Production Example 3 Production of Condensation Product No. 3

With reference to Production Example 1 disclosed in JapanesePre-examination Patent Publication (kokai) No. 57-164107, a polymerscale preventive agent was produced.

Into a pressure-resistant reaction vessel, 250 mols (36.0 kg) of1-naphthol and 180 liters of 1N-NaOH aqueous solution (containing 180mols or 7.2 kg of NaOH) were charged, and the temperature was raised to70° C. with stirring. Next, to the reaction mixture, formaldehyde (19.75liters of 38 w/v % aqueous solution, 250 mols) was dropwise added over aperiod of 1.5 hours. During the addition, the internal temperature ofthe reaction vessel was controlled so as not to exceed 80° C. Then, thereaction mixture was cooled to 60° C. over a period of 3 hours with thestirring kept. Next, the temperature of the reaction mixture was raisedto 98° C. to carry out the reaction at 98° C. for 1.5 hours. Thereafter,the reaction mixture was cooled to obtain an alkaline solution of acondensation product (Condensation Product No. 3). The CondensationProduct No. 3 had a weight-average molecular weight of 2,400.

Production Example 4 Production of Condensation Product No. 4

With reference to Coating Compound Synthesis 2 disclosed in JapanesePre-examination Patent Publication (kokai) No. 57-192413, a scalepreventive agent was produced.

Into a pressure-resistant reaction vessel, 100 mols (12.6 kg) ofpyrogallol and 100 liters of water were charged, and the pyrogallol wasdissolved in the water. Next, to the solution obtained, 200 mols (21.2kg) of benzaldehyde and 300 mols (29.4 kg) of phosphoric acid wereadded, and the mixture thereof was reacted at 95° C. for 10 hours. As aresult, a water-insoluble reddish brown product was obtained. Thiswater-insoluble product was washed with ether, followed by extractionwith methanol to extract a methanol-soluble matter from thewater-insoluble product. Then, the methanol was removed from the extractby drying to obtain Condensation Product No. 4 (pyrogallol-benzaldehydecondensate), as a residue, which had a weight-average molecular weightof 4,500.

Production Example 5 Production of Condensation Product No. 5

With reference to Production Example I disclosed in Japanese PatentPublication (kokoku) No. 59-16561, a scale preventive agent wasproduced.

Into a pressure-resistant reaction vessel, 100 mols (10.8 kg) ofm-phenylenediamine, 200 mols (22.0 kg) of resorcinol and 1.04 kg of 35%hydrochloric acid (10 mols as HCl) as a catalyst were charged, and thetemperature was raised to 305° C. Immediately after the mixture in thereaction vessel reached 305° C., it was cooled. The water vapor evolvedin the course of the raise in temperature and the reaction was removed,and the internal pressure was kept at 150 kPa or below. After cooling,the resulting m-phenylenediamine/resorcinol condensate was pulverized,followed by washing with water, filtering and drying, to obtainCondensation Product No. 5 which had a weight-average molecular weightof 4,000.

Production Example 6 Production of Condensation Product No. 6

With reference to Production Example VI disclosed in Japanese PatentPublication (kokoku) No. 59-16561, a scale preventive agent wasproduced.

Into a pressure-resistant reaction vessel, 100 mols (10.9 kg) ofp-aminophenol and 0.99 kg of 30% hydrochloric acid (9.5 mols as HCl)were charged, and the temperature was raised to 169° C. Immediatelyafter the reaction mixture reached 169° C., 18 liters of xylene wasslowly added. The xylene was added so that the water formed during thecondensation reaction was removed as an azeotropic mixture. Next, thetemperature of the reaction mixture was raised to 222° C., and thereaction was carried out at 222° C. for 3 hours. The xylene-water mixedvapor evolved during the reaction was removed, and the internal pressurewas kept at 150 kPa or below. After the reaction was carried out for 3hours, the reaction mixture was cooled. The reaction product(Condensation Product No. 6) obtained was solid. Next, the reactionproduct was pulverized into fine particles, and thereafter washed withwater, followed by filtration and then drying to obtain the CondensationProduct No. 6 which had a weight-average molecular weight of 2,500.

Production Example 7 Production of Condensation Product No. 7

With reference to Production Example 1 disclosed in JapanesePre-examination Patent Publication (kokai) No. 54-7487, a scalepreventive agent was produced.

Into a reaction vessel, 200 mols (22.0 kg) of resorcinol was charged,and then heated in a nitrogen atmosphere. The temperature of resorcinolwas raised to 300° C., and the reaction was carried out at 300° C. for 8hours, followed by cooling. The solid self-condensed resorcinol thusobtained was pulverized to obtain Condensation Product No. 7 which had aweight-average molecular weight of 1,700.

Production Example 8 Production of Condensation Product No. 8

(1) Synthesis of a 2,3-dihidoroxynaphthalene dimer compound:

Into a flask having an inner capacity of 3 liters provided with a refluxcondenser, 1350 mL of methanol was charged and then 144 g (0.9 mol) of2,3-dihydoroxynaphthalene was dissolved therein. After the dissolution,the temperature was raised to 65° C., and 243 g (0.9 mol) of ferricchloride hydrate(FeCl₃·6H₂O) dissolved in 450 mL of methanol was addeddropwise to the solution obtained under reflux over 30 minutes. Afterthe addition, reaction was continued under reflux for 5 hours.Subsequently, the reaction solution was transferred into 4.5 liters of adiluted hydrochloric acid and then the resulting mixture was stirred for12 hours, to produce a dimer compound of 2,3-dihydroxynaphthalene. Thereaction solution thus obtained was filtered to remove the solvents, andthereafter the residual matter was washed with two liters of pure waterfor two hours. The solution was filtered again to remove the ferricchloride hydrate(FeCl₃·6H₂O).

The dimer compound of 2,3-dihydroxynaphthalene obtained was dried in adryer at 40° C.

(2) Into a 3 liter-flask provided with a reflux condenser, one liter ofpure water was charged, and then 5 g of sodium hydroxide and 50 g of the2,3-dihydroxynaphthalene dimer compound obtained as above were charged.Subsequently, after the temperature was raised to 70° C., 12.75 g of 37%aqueous formaldehyde solution dissolved in 237.3 g of distilled water,was added dropwise over 30 minutes. After the addition, reaction wascontinued at the same temperature for five hours, and then thetemperature was raised to 95° C. and reaction was continued for furthertwo hours, thereby Condensation Product No. 8 being obtained.Incidentally, the reactions were all carried out in N₂ atmospheres.

After the completion of the reactions, Condensation Product No. 8 wascooled to 25° C., and then preserved in an N₂ atmosphere. Theweight-average molecular weight was 22,000.

Production Examnple 9 Production of Condensation Product No. 9

Into a reaction vessel having an inner capacity of 2 liters providedwith a reflux condenser, a mixed solvent of methanol (450 g) with water(450 g) was charged and subsequently 100 g of α-naphthoquinone and 10 gof sodium hydroxide were charged. Then, the internal temperature of thereaction vessel was raised to 50° C. and the mixture in the reactionvessel was reacted at 50° C. for 24 hours, followed by cooling the sameto room temperature. Thus, a solution of Condensation Product No. 9 wasobtained. The Condensation Product No. 9 had a weight-average molecularweight of 3,000.

Production Example 10 Production of Condensation Product No. 10

In a 20 L internal volume reaction vessel having a reflux condenser, 1.5kg of 1-naphthol and 7.5 L of toluene were put, and the mixture obtainedwas heated with stirring until the toluene became refluxed. Under refluxat this temperature, 930 ml of sulfur monochloride was added dropwiseover a period of 6 hours, and thereafter the mixture obtained was keptfor 1 hour at that temperature. After the reaction mixture was cooled, 5L of hexane was added with stirring to cause the reaction product toprecipitate. Thereafter, the reaction product was filtered, and thendried to obtain Condensation Product No. 10. The Condensation ProductNo. 10 had a weight-average molecular weight of 1,200.

Production Example 11 Production of Condensation Product No. 11

In a 20 L internal volume reaction vessel having a reflux condenser, 6.7L of water, 1,786 g (9.5 mols) of 6-hydroxy-2-naphthoic acid, 55 g (0.5mol) of resorcinol and 620 g (15.5 mols) of NaOH were put, andthereafter the mixture obtained was heated to 50° C. with stirring. Atthe time it reached 50° C., 1.0 L of an aqueous 30 w/v % formaldehydesolution (formaldehyde: 10 mols) was added dropwise over a period of 1hour. During the addition, the internal temperature of this reactionvessel was so controlled not to become higher than 55° C. Next, thereaction mixture thus obtained was heated to 85° C., and was allowed toreact at 85° C. for 3 hours. Thereafter, the reaction mixture obtainedwas cooled to obtain an alkaline solution of a condensation product(Condensation Product No. 11). The Condensation Product No. 11 had aweight-average molecular weight of 2,200.

Preparation of First Coating liquid Preparation of first coating liquidNos.101-114

Using a conjugated bond compound, pH adjuster and solvent shown in Table1, first coating liquids were so prepared as to meet the conditionsshown in Table 1 [conjugated bond compound (A), auxiliary agent (B), pHadjuster, (A)/(B) weight ratio, (A)+(B) total concentration, solventcomposition, and pH]. In the table, the coating liquid No. 102 is acoating liquid containing a scale preventive agent in a lowconcentration, to be used for spray coating.

Preparation of coating liquid Nos. 115-119

The following compounds I to V were used as a conjugated bond compound.

I: phenanthrene-1,4-quinone

II: quinizarine

III: 1,5-diaminonaphthalene

IV: 1,4-diaminoanthrathene

V: 1,2-naphthoquinone

Using a compound above, a pH adjuster and a solvent shown in Table 2,first coating liquids were so prepared as to meet the conditions shownin Table 2 [conjugate bond compound (A), auxiliary agent (B), pHadjuster, (A)/(B) weight ratio, (A)+(B) total concentration, solventcomposition, and pH].

In the following table, the condensation product is simply called “CP”.For example, “CP 9” stands for “Condensation Product No. 9”.

TABLE 1 (A) + (B) Coating First Conjugated (A/B) liquid coating π bondAuxiliary pH (weight concentration Coating liquid No. compound (A) agent(B) adjuster ratio) (wt %) Solvent liquid pH 101 CP9 None NaOH — 6 water12.5 102 CP9 Colloidal silica NaOH 100/100 0.5 water 10.5 103 CP1 NoneNaOH — 4 water/methanol 70/30 12.5 104 CP2 none KOH — 4 Water 13.0 105CP3 none NaOH — 4 water 12.5 106 CP4 none ethylenediamine — 4water/methanol 80/20 9.0 107 CP5 none NaOH — 3.5 water 13.0 108 CP6 noneKOH — 3.5 water 12.0 109 CP7 none nitric acid — 5 water 4.5 110 CP8 noneNaOH — 5 water 12.5 111 CP9 none ethylenediamine — 5 water 11.0 112 CP10 none NaOH — 4 water 12.0 113  CP11 none NaOH — 4 water 12.5 114 CP10 none none — 4 N-methyl-2-pyrrolidone —

TABLE 2 (A) + (B) Coating First Conjugated (A/B) liquid coating π bondAuxiliary pH (weight concentration Coating liquid No. compound (A) agent(B) adjuster ratio) (wt %) Solvent liquid pH 115 I none ethylenediamine— 4 water 13.0 116 II none NaOH — 4 water 12.5 117 III none none — 4methanol — 118 IV none none — 4 mehtanol — 119 V none none — 4N-methyl-2-pyrrolidone —

Preparation of Second Coating liquid Preparation of second coatingliquid Nos.201-218

Using an auxiliary agent (B), a pH adjuster and a solvent shown inTables 3 and 4, second coating liquids were so prepared as to meet theconditions shown in Tables 3 and 4 [auxiliary agent (B), weight ratio of(1)/(2), (3) or (4), total concentration of auxiliary agent (B),solvent, pH adjuster, and pH]. In the Table 3, the coating liquid No.202 is a comparative coating liquid containing a scale preventive agentin a relatively low concentration, to be used for spray coating. Incoating liquids making use of a water-soluble polymeric compound, whenthe water-soluble polymeric compound (B) was soluble with difficulty,the solvent was heated to about 70° C. to effect dissolution.

TABLE 3 Auxiliary agent (B) Second Water- Weight ratio Total coatingsoluble Inorganic Inorganic Acid of (1)/(2), concentration pH Coatingliquid polymer (1) colloid (2) salt (3) (4) (3) or (4) of (B) (wt %)Solvent adjuster liquid pH 201 polyvinyl — — — — 1.5 water none 7.5pyrrolidone 202 polyvinyl colloidal — — 100/50 0.6 water none 8.5pyrrolidone silica 203 — colloidal — — — 3.0 water none 9.5 silica 204 —— water — — 1.5 water none 12.5 glass 205 — — — phitic — 2.0water/methanol 70/30 none 1.3 acid 206 polyvinyl — — — — 2.0 water none7.5 pyrrolidone 207 gelatin — — — — 1.0 water N_(a)OH 8.5 208 pectinacid — — — — 1.5 water none 7.0 209 casein — — — — 3.5 water/ethanol90/10 KOH 7.5

TABLE 4 Auxiliary agent (B) Second Water- Weight ratio Total coatingsoluble Inorganic Inorganic Acid of (1)/(2), concentration pH Coatingliquid polymer (1) colloid (2) salt (3) (4) (3) or (4) of (B) (wt %)Solvent adjuster liquid pH 210 polyvinyl colloidal silica — — 100/50 1.5water ethylenediamine 9.0 pyrrolidone 211 polyvinyl — pyrophosphoric —100/10 1.1 water none 7.0 pyrrolidone acid calcium 212 polyvinyl — —phitic acid  100/100 2.0 water none 1.5 pyrrolidone 213 polyvinyl — —sulfuric acid 100/50 1.5 water none 1.0 pyrrolidone 214 gelatincolloidal silica — —  100/100 1.0 water N_(a)OH 9.0 215 gelatin — —phosphoric acid 100/50 1.5 water none 1.5 216 polyacrylic —pyrophosphoric — 100/20 1.2 water none 2.5 acid acid calcium 217polyacrylic — — tannic acid  100/100 2.0 water none 1.0 acid 218 pecticacid — — phosphomolybdic 100/50 1.5 water none 1.0 acid

Example 1

FIG. 2 schematically illustrates the arrangement of a polymerizationapparatus. In respect to a polymerization vessel, the same elements asin FIG. 1 are denoted with the same numerals. The following experimentswere made using a polymerization apparatus shown in FIG. 2. In FIG. 2, a2 m³ internal volume polymerization vessel 1 made of SUS 316L stainlesssteel is equipped with a stirrer 21 having stirring blades 20 (astirring motor is not shown), a heating-cooling jacket 2, a manhole 22,a baffle 23 and other fittings (not shown) usually providing forpolymerization vessels for polymerizing vinyl chloride. A line 24connected to the upper part of the polymerization vessel 1 is a line forcharging materials. To the line 24, branch lines such as a vinylchloride monomer (VCM) charging line 24 a, a catalyst solution chargingline 24 b, a suspending agent charging line 24 c and a pure-watercharging line 24 d are connected as shown in FIG. 2. This charging lines24 and 24 a-24 d are provided with valves V1, V2, V3, V4 and V5 at thepositions shown in the drawing. A line 25 also connected to the upperpart of the polymerization vessel 1 is provided in order to evacuate theinside of the polymerization vessel 1 and to recover monomers, and isled to a gas holder 27 through a line 26 branched from the line 25. Amonomer recovery line 28 is led out of the gas holder 27, and a line 29led out of the gas holder 27 is connected to the line 25 so as to beused in pressure equalization described later. These lines 25, 26, 28and 29 are provided with valves V6, V7, V8, V9, V10, V11, V12 and V13.The line 26 is branched into a line 26 a provided with a vacuum pump 30so that monomers can be recovered and a line 26 b with no pump, andthereafter the branched lines are joined together to form a single linewhich is connected to the gas holder 27. To the upper part of thepolymerization vessel 1, a line 31 is also connected in order to washthe inside of the polymerization vessel with water. The line 31 isprovided with valves 14 at the position shown in the drawing and has anozzle 32 at the end introduced inside the vessel. To the upper part ofthe polymerization vessel 1, a first coating liquid feed line 34 and asecond coating liquid feed line 35 are connected to a coating liquidfeed line 33 through valves V17 and V18, respectively, as shown in thedrawing. Further, to the line 33 a steam feed line 36 is connected via avalve V19. The line 33 is provided at its end located inside the vesselwith a coating ring 4 to which coating nozzles 3 a, 3 b are attached.This line 33 is provided with valves V15 and V16 at the positions shownin the drawing. To the bottom of the polymerization vessel 1, a line 37is connected, which is branched into a line 38 a through which polymerslurry is led to a blow-down tank and a line 38 b through which thecoating liquids or washing water is discharged. The lines 38, 38 a and38 b are provided with valves V20, V21 and V22 at the positions shown inthe drawing.

In each experiment, the coating liquids were previously coated on thepolymerization vessel inner wall surfaces and others in the manner asdescribed below, followed optionally by drying to form a coating film.In the polymerization vessel, vinyl chloride monomers were polymerizedin the manner as described below.

(1) Coating and drying:

The coating film is formed on the inner wall surfaces and others of thepolymerization vessel of the polymerization apparatus shown in FIG. 2,by a method of a), b), c) or d) below. Methods a), b) and c) are methodsof comparative examples. In the initial stage of each method, all of thevalves are closed.

a) One-liquid spray coating and drying:

Hot water is passed through the jacket 2 to keep the polymerizationvessel 1 inner wall surfaces heated to a temperature of 70° C. (Time forpreheating with the jacket: 10 minutes). The valves V17, V16, V15, V20and V22 are opened, and the first coating liquid containing a scalepreventive agent is coated at a flow rate of 5 L (liter)/min for 1.5minutes. The valves V17, V16, V15, V20 and V22 are closed, and then thevalves V6, V8, V13, and V9 are opened, where the vacuum pump 30 isactuated to evacuate the inside to 8.0 kPa (−700 mmHg and the wetcoating is dried (drying is necessary; drying time: 25 minutes) to forma coating film. Thereafter, the vacuum pump is stopped and the valvesV8, V13, and V9 are closed. Next, the valves V7 and V10 are opened tomake the internal pressure of the polymerization vessel 1 equal to theinternal pressure of the gas holder 27. Thereafter, the valves V6, V7and V10 are closed. The feeding of hot water to the jacket 2 is stopped.

b) Two-liquid two-stage spray coating and drying:

Hot water is passed through the jacket 2 to keep the polymerizationvessel 1 inner wall surfaces heated to a temperature of 70° C. (Time forpreheating with the jacket: 10 minutes). The valves V17, V16, V15, V20and V22 are opened, and the coating liquid containing a scale preventiveagent (for under coating) is coated at a flow rate of 5 L/min for 1.5minutes. The valves V17, V16, V15, V20 and V22 are closed, and then thevalves V6, V8, V13, and V9 are opened, where the vacuum pump 30 isactuated to evacuate the inside to 8.0 kPa (−700 mmHg) and the wetcoating is dried (drying is necessary; drying time: 25 minutes) to forma first layer. Thereafter, the vacuum pump is stopped and the valves V8,V13, and V9 are closed. Next, the valves V7 and V10 are opened to makethe internal pressure of the polymerization vessel 1 equal to theinternal pressure of the gas holder 27. Thereafter, the valves V6, V7and V10 are closed. Next, the valves V18, V16, V15, V20 and V22 areopened, and the coating liquid containing a polymer scale preventiveauxiliary agent (for top coating) is coated on the above first layer ata flow rate of 5 L/min for 1.5 minutes. The valves V18, V16, V15, V22and V20 are closed, and then the valves V6, V8, V13, and V9 are opened,where the vacuum pump 30 is actuated to evacuate the inside to −700 mmHg and the wet coating is dried (drying is necessary; drying time: 25minutes) to form a second layer. Thereafter, the vacuum pump is stoppedand the valves V8, V13, and V9 are closed. Next, the valves V7 and V10are opened to make the internal pressure of the polymerization vessel 1equal to the internal pressure of the gas holder 27. Thereafter, thevalves V6, V7 and V10 are closed. The feeding of hot water to the jacket2 is stopped.

c) One-liquid steam coating (and simultaneous drying):

Hot water is passed through the jacket 2 to keep the polymerizationvessel 1 inner surfaces heated to a temperature of 70° C. (Time forpreheating with the jacket: 10 minutes). The valves V19, V22, V20, V15and V16 are opened, and 392 kPa·Gauge (4 kgf/cm²·G) (143° C.) of steamis blown into the polymerization vessel at a flow rate of 240 kg/Hr for3 minutes. After the inside of the vessel is pre-heated, the valve V17is opened, and the coating liquid containing a scale preventive agent iscoated and dried simultaneously at a flow rate of 0.2 L/min for 2minutes while utilizing the steam as a carrier. Thereafter, the valvesV19, V22, V20, V15, V16 and V17 are closed. The feeding of hot water tothe jacket 2 is stopped.

d) Two-liquld one-stage steam coating (and simultaneous drying):

(1) Coating and drying

Hot water is passed through the jacket 2 to keep the polymerizationvessel 1 inner wall surfaces heated to a temperature of 70° C. (Time forpreheating with the jacket: 10 minutes). The valves V9, V22, V20, V15and V16 are opened, and 392 kPa·Gauge (4 kgf/cm²·G) (143° C.) of steamis blown into the polymerization vessel 1 at a flow rate of 240 kg/Hrfor 3 minutes. After the inside of the vessel is pre-heated, the valveV17 is opened and, substantially at the same time when the valve 17 isopened, the valve 18 is opened, where the first coating liquidcontaining a scale preventive agent and the second coating liquidcontaining an auxiliary agent are coated and dried simultaneously at aflow rate of 0.2 L/min for 2 minutes and at a flow rate of 0.1 L/min for2 minutes, respectively, while utilizing the steam as a carrier, to forma coating film. Thereafter, the valves 17 and 18 are closed. Furtherthereafter, the valves V19, V22, V20, V15 and V16 are closed. Thefeeding of hot water to the jacket 2 is stopped.

(2) Second water washing for inside of the vessel:

The valves V14, V20, V22, V6, V7 and V10 are opened to wash the insideof the polymerization vessel with water, and the wash water isdischarged to a waste water tank. The valves V14, V20 and V22 areclosed.

The time for washing with water is four (4) minutes when the method a)or b) is used, and it is one (1) minute when the method c) or d) isused.

(3) Charging:

The valves V1, V2 and V3 are opened, and 200 parts by weight of purewater, 0.022 part by weight of partially saponified polyvinyl alcoholand 0.028 part by weight of hydroxymethyl cellulose are charged into thepolymerization vessel 1. The valves V1, V2, V3, V6, V7 and V10 areclosed.

Next, the valves V1 and V5 are opened, and 100 parts by weight of vinylchloride monomer (VCM) is charged. Then the valve V5 is closed. Next,with the charged materials being stirred, the valve V4 is opened, and0.03 part by weight of t-butyl peroxyneodecanate is charged. Then thevalves V1 and V4 are closed.

(4) Polymerization:

Hot water is passed through the jacket 2 to raise the temperature whilestirring the materials charged. At the time the internal temperature hasreached 52° C., cooling water is passed through the jacket 2 to maintainthe internal temperature at 52° C., where the polymerization is carriedout. At the time the internal pressure has dropped to 490 kPa·Gauge (5kgf/cm²·G), the polymerization is terminated.

(5) Gas discharging:

The valves V6, V8, V12 and V9 are kept open, and gas is discharged tothe gas holder 27 until the internal pressure returns to substantiallythe atmospheric pressure. Thereafter, the valves V12, V8 and V9 areclosed. Then the valves V11 and V10 are opened, and monomers recoveredin the gas holder 27 is sent to the step of recovering the VCM throughline 28. Thereafter, the valves V11 and V10 are closed.

(6) Pressure equalization:

The valves V7 and V10 are opened, and the internal pressure of thepolymerization vessel 1 and the internal pressure of the gas holder 27are made equal (pressure equalization).

(7) Slurry withdrawing:

The valves V20 and V21 are opened, and polymerization slurry iswithdrawn out of the vessel to the blow-down tank (not shown). Thepolymerization slurry withdrawn to the blow-down tank is thereafterdehydrated and dried to become a vinyl chloride polymer product.

(8) Vessel-inside first washing:

The valve V14 is opened. The inside of the polymerization vessel 1 iswashed with water, and the wash water is sent to the blow-down tank.Thereafter, the valves V14, V20, V21, V6, V7 and V10 are closed. Duringthis washing of the inside of the vessel, hot water is passed throughthe jacket 2 to keep the temperature of the polymerization vessel wallsurfaces at 70° C.

The coating solution and coating film forming method used in eachexperiment are shown in Table 5.

In each experiment, the operation from the (1) coating and drying up tothe (8) first washing after completion of polymerization is set as onebatching. The like operation was repeated by the number of batching asshown in Table 7.

TABLE 5 First Second coating coating Experiment liquid liquid No.Coating film forming method No. No. 101 d)two-liquid one-stage steamcoating 101 201  102* c)one-liquid steam coating 101 none  103*a)one-liquid spray coating 102 none  104* a)one-liquid spray coatingnone 202  105* b)two-liquid spray coating 102 202 106 d)two-liquidone-stage steam coating 111 203 107 d)two-liquid one-stage steam coating111 204 108 d)two-liquid one-stage steam coating 111 205 109d)two-liquid one-stage steam coating 111 206 110 d)two-liquid one-stagesteam coating 111 207 111 d)two-liquid one-stage steam coating 111 208112 d)two-liquid one-stage steam coating 103 209 113 d)two-liquidone-stage steam coating 104 210 114 d)two-liquid one-stage steam coating105 211 115 d)two-liquid one-stage steam coating 106 212 116d)two-liquid one-stage steam coating 107 213 117 d)two-liquid one-stagesteam coating 108 214 118 d)two-liquid one-stage steam coating 109 215119 d)two-liquid one-stage steam coating 110 216 120 d)two-liquidone-stage steam coating 111 217 121 d)two-liquid one-stage steam coating112 218 122 d)two-liquid one-stage steam coalting 113 211 123d)two-liquid one-stage steam coating 114 211 124 d)two-liquid one-stagesteam coating 105 212 125 d)two-liquid one-stage steam coating 105 215126 d)two-liquid one-stage steam coating 115 215 127 d)two-liquidone-stage steam coating 116 216 128 d)two-liquid one-stage steam coating117 217 129 d)two-liquid one-stage steam coating 118 218 130d)two-liquid one-stage steam coating 119 215 (Remarks) *ComparativeExample

<Evaluation>

In each experiment, measurement was made on the following items to makeevaluation. The results are shown in Tables 6, 7 and 8.

Time required to form coating films

The time taken for the formation of coating films in Examples andComparative Examples is shown in Table 6.

Measurement of the amount of polymer scale deposited

In each experiment, after the final batching was completed, polymerscale built-up at the liquid-phase portion in the polymerization vesseland polymer scale built-up on the surfaces of stirring blades andbaffles and on and in the vicinity of the boundary between the gas-phaseportion and the liquid-phase portion were determined in the followingway.

The scale deposited in an area of 10 cm×10 cm at a surface to bemeasured was scraped off with a spatula as completely as can beconfirmed with the naked eye, and then the scraped scale was weighed ona balance. The measured value was multiplied by 100 to obtain the amountof the deposited polymer scale per area of 1 m². The results are givenin Table 7.

Measurement of fish eyes

Fish eyes produced when a polymeric product obtained at the finalbatching in each experiment is formed into sheet, were measured by themethod below.

A hundred (100) parts by weight of a polymer obtained, 50 parts byweight of dioctyl phthalate (DOP), 1 part by weight of dibutyltindilaurate, 1 part by weight of cetyl alcohol, 0.25 part by weight oftitanium oxide and 0.05 part by weight of carbon black were mixed. Theresulting mixture was kneaded at 150° C. for 7 minutes with 6 inchrolls, and then formed into a sheet 0.2 mm thick. The obtained sheet wasexamined for the number of fish eyes per 100 cm² by light transmission.The results are given in Table 8.

Measurement of luminosity index (L value)

Measurement of luminosity index (L value) of a sheet formed from apolymer obtained in each experiment was carried out, according to themethod below. The results are given in Table 8.

A hundred (100) parts by weight of an obtained polymer, 1 part by weightof a dibutyltin laurate stabilizing agent (TS-101, product of AkisimaChemical Co.) and 0.5 part by weight of a cadmium organic complexstabilizing agent (C-100J, product of Katsuta Kako Co.), and 50 parts byweight of dioctyl phthalate as a plasticizer were kneaded at 160° C. for5 minutes with a twin roll mill, and then formed into a sheet 1 mmthick. Subsequently, this sheet was placed in a molding frame measuring4×4×1.5 cm, heated at 160° C. under a pressure of 6.37 to 6.87 MPa·Gauge(65 to 70 kgf/cm²·G) to prepare a test specimen. This test specimen wasmeasured for luminosity index L in the following way.

First, the stimulus value Y of XYZ color system is determined by thephotoelectric tristimulus colorimetry using the standard light C,photoelectric colorimeter (Color measuring color difference meter ModelZ-1001DP, product of Nippon Denshoku Kogyo K.K.) in accordance with JISZ 8722. As the geometric condition of illumination and light reception,the condition d defined in section 4.3.1 of JIS Z 8722 is adopted.

Next, from the stimulus value Y obtained, the L value is calculatedbased on the Hunter's color difference equation: L=10Y^(½) described inJIS Z 8730 (1980). The greater the value of L, the higher the whitenessis evaluated, namely, the better the initial anti-discolorationproperties are.

Examination of colored particles:

A mixture of 100 parts by weight of the polymer obtained in eachexperiment after the final batching was completed, 2 parts by weight ofa stabilizer TVS N-2000E (available from Nitto Kasei Co., Ltd.) and 20parts by weight of a plasticizer dioctyl phthalate was thoroughlykneaded and thereafter put in a molding frame of 160 mm×130 mm×3 mm, andwas subsequently pressure-molded at a temperature of 175° C. and apressure of 3.43 MPa·Gauge (35 kgf/cm²·G) to obtain a sample forexamination. Samples thus obtained were examined visually on the numberof colored particles. The results are shown in Table 8.

TABLE 6 Spray coating Steam coating b) Two- d) Two- liquid liquid a)One- two- c) One- one- liquid stages liquid stage Jacket pre-heatingtime (min) 10.0 10.0 10.0 10.0 Steam pre-heating time (min) 0 0 3.0 3.0First-liquid coating time (min) 1.5 1.5 2.0 2.0 First-liquid drying time(min) 25.0 25.0 0 0 Second-liquid coating time (min) 0 1.5 0 2.0Second-liquid drying time (min) 0 25.0 0 0 Water washing time (min) 4.04.0 1.0 1.0 (second washing) Total time (min) 40.5 67.0 16.0 16.0

TABLE 7 Scale build-up (g/m2) Liquid Vicinity of Experiment Number ofphase gas-liquid Stirring No. batches portion interface blade Baffle 101250 0 0 0 3  102* 250 0 45  8 10   103* 250 0 0 85  120   104*  20 26 185  270  335   105* 250 0 0 51  65  106 250 0 0 0 7 107 250 0 0 0 6 108250 0 0 0 4 109 250 0 0 0 5 110 250 0 0 0 4 111 250 0 0 0 6 112 250 0 00 5 113 250 0 0 0 7 114 250 0 0 0 7 115 250 0 0 0 4 116 250 0 0 0 5 117250 0 0 0 5 118 250 0 0 0 4 119 250 0 0 0 7 120 250 0 0 0 5 121 250 0 00 7 122 250 0 0 0 7 123 250 0 0 0 6 124 250 0 0 0 5 125 250 0 3 2 7 126250 0 4 2 8 127 250 0 3 3 8 128 250 0 3 3 7 129 250 0 4 3 9 130 250 0 32 7 (Remarks) *Comparative Example

TABLE 8 Scale build-up and quality Experiment Fish eyes Luminosity indexColored particles No. (number) (L value) (number) 101 1 73.0 3  102* 19 72.0 25   103* 32  72.0 76   104* 110  72.0 82   105* 11  72.0 31  106 273.0 3 107 1 73.0 2 108 2 73.0 4 109 1 73.0 2 110 1 73.0 3 111 1 73.0 2112 1 73.0 2 113 2 73.0 4 114 2 73.0 4 115 1 73.0 3 116 2 73.0 5 117 273.0 3 118 1 73.0 3 119 1 73.0 3 120 1 73.0 3 121 1 73.0 4 122 2 73.0 5123 2 73.0 5 124 2 73.0 4 125 7 73.0 9 126 5 73.0 8 127 6 73.0 10  128 673.0 9 129 5 73.0 7 130 7 73.0 10  (Remarks) *Comparative Example

What is claimed is:
 1. A process for producing a polymer by polymerizingin a polymerization vessel a monomer having an ethylenic double bond,wherein said polymerization vessel has a polymer scale preventivecoating film on its inner wall surfaces and other surfaces with whichthe monomer comes into contact during polymerization; said coating filmbeing formed by coating a first coating liquid containing a compoundselected from the group consisting of an aromatic compound having 5 ormore conjugated bonds and a heterocyclic compound having 5 or moreconjugated bonds and a second coating liquid containing at least onehydrophilic compound selected from the group consisting of awater-soluble polymeric compound, an inorganic colloid, an inorganicsalt and an acid; said first coating liquid and said second coatingliquid being simultaneously coated by means of steam as a carrier. 2.The process of claim 1, wherein said conjugated bond-containing compoundcontained in the first coating liquid is an aromatic compoundcondensation product having a weight-average molecular weight of 500 ormore.
 3. The process of claim 2, wherein said weight-average molecularweight ranges from 500 to 70,000.
 4. The process of claim 2, whereinsaid aromatic compound condensation product is selected from the groupconsisting of aldehyde compound/aromatic hydroxyl compound condensationproducts, pyrogallol/acetone condensation products, polyhydric phenolself-condensation products, polyhydric naphthol self-condensationproducts, aromatic amine compound condensation products, quinonecompound condensation products, and sulfide compounds of aromatichydroxyl compounds.
 5. The process of claim 2, wherein said aromaticcompound condensation product is an aldehyde compound/aromatic hydroxylcompound condensation product or a quinone compound condensationproduct.
 6. The process of claim 1, wherein said first coating liquid isa solution containing a compound selected from the group consisting ofpyrogallol/acetone condensation products, polyhydric phenolself-condensation products and polyhydric naphthol self-condensationproducts in water or a mixed solvent of water with a hydrophilic organicsolvent miscible with water, and having a pH of 2.0 to 6.5.
 7. Theprocess of claim 1, wherein said first coating liquid is a solutioncontaining a compound selected from the group consisting of condensationproducts of aldehyde compound/aromatic hydroxyl compound, condensationproducts of an aromatic amine compound, and condensation products of aquinone compound in water or a mixed solvent of water with a hydrophilicorganic solvent miscible with water, and having a pH of 7.5 to 13.5. 8.The process of claim 1, wherein said first coating liquid contains theconjugated bond-containing compound in a concentration ranging from 1.0to 25.0% by weight.
 9. The process of claim 1, wherein saidwater-soluble polymeric compound contains a water-soluble polymericcompound selected from the group consisting of water-soluble hydroxylgroup-containing polymeric compounds, water-soluble amphoteric polymericcompounds, water-soluble anionic polymeric compounds and water-solublecationic polymeric compounds, thereby the resulting coating filmcontaining the same.
 10. The process of claim 1, wherein said inorganicsalt is a compound selected from the group consisting of alkaline metalsilicates and inorganic salts of alkaline-earth metals, thereby theresulting coating film containing the same.
 11. The process of claim 1,wherein said hydrophilic compound is methyl cellulose, hydroxyethylcellulose, hydroxyethyl methyl cellulose, polyvinyl alcohol, partiallysaponified polyvinyl alcohol, glue, casein, gelatin, chitosan,polyacrylic acid, alginic acid, polymethacrylic acid, pectic acid,carragheenin, hyaluroic acid, carboxymethyl cellulose, polyvinylpyrrolidone or a styrene-maleic anhydride copolymer; or a colloid ofoxides or hydroxides of metals selected from aluminum, titanium,zirconium, tin and iron, or colloidal silica; or magnesium carbonate,calcium carbonate, magnesium phosphate, calcium phosphate, calciumpyrophosphate, calcium dihydrogenpyrophosphate, barium phosphate,calcium sulfate, calcium borate, magnesium hydroxide, calcium hydroxide,barium hydroxide, magnesium chloride or calcium chloride; or acombination of two or more thereof, thereby the resulting coating filmcontaining the same.
 12. The process of claim 1, wherein the secondcoating liquid contains said hydrophilic compound in a concentrationranging from 0.01 to 20% by weight in water or a mixed solvent of waterwith a hydrophilic solvent miscible with water.
 13. The process of claim1, wherein both said steam used in the application of said first coatingliquid and second coating liquid has a temperature of 120 to 260° C. anda pressure of 0.20 to 3.43 MPa Gauge (2 to 35 kgf/cm² G).
 14. Theprocess of claim 13, wherein said steam has a temperature of 130 to 200°C. and a pressure of 0.27 to 1.96 Mpa Gauge (2.8 to 20 kgf/cm² G). 15.The process of claim 1, wherein, in the application of said firstcoating liquid and second coating liquid, the total of the first andsecond coating liquids (L) and the steam (G) are mixed in a ratio (L/G)of from 0.005 to 0.8 in terms of flow rate ratio on the basis of weight.16. The process of claim 15, wherein said ratio of L/G is in a range of0.01 to 0.2.